Building the $100 precharged pneumatic air rifle: Part 1

by Tom Gaylord, a.k.a. B.B. Pelletier

Airgun manufacturers: If you read this blog, today’s report is one you’ll want to pay attention to! When I announced last Friday that I would be writing this, I received more interest than any subject that’s ever been raised on this blog. That makes this a subject of primary importance to anyone who wants to know what the consumer wants.

Blog readers: Many of you have not read or perhaps not understood all that I’ve said about this project. I am therefore going to explain it now in clear terms, so that everybody will know what I’m talking about. This project is a proof of concept. It is not a new airgun that’s about to be built. I don’t know if it will ever be made; and if it is, it probably won’t look like what you’re about to see. This is a single airgun that incorporates the features I’ve envisioned in a PCP that could retail for less than $100. A lot less, if you follow carefully.

The base gun used as the starting point for the project is a Crosman 2100B. That’s a multi-pump pneumatic that has a lot of plastic on it and a soda-straw barrel. It’s one of those dual-ammo rifles that shoots both BBs and pellets but has a rifled bore. As this report is written, Pyramyd Air has them priced at $59.95.

$100 PCP
Dennis Quackenbush turned a Crosman 2100B multi-pump into a PCP by adding a reservoir where the pump mechanism used to be.

$100 PCP forearm tip
The forearm tip no longer has anything to attach to. It used to be the anchor for the pump pivot.

To convert the rifle, Dennis had to remove the multi-pump mechanism (pump linkage, pump anchor, pump head and rod and connecting hardware), including the tube that houses it. A steel hydraulic tube was installed in its place. Dennis chose SAE 1026 tubing that’s 0.75″ diameter on the outside and has a wall thickness of 0.083 inches. That gives the tube a burst pressure rating of 14,386 psi — more than enough for this project. In fact, to use Dennis’ words, it’s overkill.

A tube with a thinner wall thickness would have more internal volume, but it would be marginal for the threads that Dennis cut inside the tube to attach to the brass firing valve. Thinner tubing would have to be pinned instead of threaded. It would still work fine and the burst rating would still be many times the expected operating pressure.

To complete the gun, Dennis had to thread the other end to accept a fill nipple. He also had to change the firing valve return spring because the thick-walled tube didn’t allow sufficient clearance for the factory spring.

Cost to build
What are we looking at? The gun costs $60. The new reservoir tube has a nominal cost of $10. The fill nipple has a small cost, along with some other small parts. And Dennis has to get paid for his time to remove the factory parts, thread the new tube on both ends, install the new tube and seal it on both ends. He also had to turn the pump arm that swings into a forearm that attaches to the pressure tube. A special barrel hanger had to be made so he didn’t need to drill and tap holes in the pressure tube. Takes about a minute to write about all the work and maybe 6-8 hours to do it. Do several and you’ll find ways to shorten the time to perhaps 4 hours.

So — those who expect Dennis to go into business making this airgun want him to fork out $75 and spend 4 hours of his time to make $25. Does that seem fair? Of course not! Even if he could cut a deal with Crosman or a distributor to lower his out-of-pocket expenses for the starter rifle, he’s still working for peanuts.

Crosman, on the other hand, could do something like this with great efficiency! They could make small adjustments to the manufacturing process upstream, so this gun wouldn’t cost them any more to build than the 2100B — or if it did cost more, the difference would be quite small.

So, why don’t “they” do it? Well, I expect our comments will provide some answers. For starters there will be those who find plastic on airguns to be poison. No plastic for them! And the soda-straw barrel will also turn them off. What are “they” trying to foist on us? Don’t “they” know that plastic and cheap barrels turn us off?

Well, I’m not doing this project for people who feel that way. This is a precharged airgun that can retail for less than $100, and corners have to be cut. We don’t ever skimp on safety, but performance? Forget performance! You’re going to get a soda-straw barrel and lots of plastic for under $100, and you’ll be happy with it.

Believe it or not, there are a lot of shooters out there who would be thrilled to get a PCP for under $100. They would accept the thin barrel and the plastic, knowing that this is the only way they will ever get close to their goal of an affordable PCP. Those are the ones I’m doing this project for. The others can buy the more expensive PCPs and make all the comparisons they want.

So what?
Is such a PCP worth the effort? What kind of velocity will it have? What kind of accuracy? How many good shots will it have per fill? Is it an airgun worth having, or is it just a dream that was poorly executed? We talk about these things on this blog all the time — but today, thanks to Dennis Quackenbush, we actually have one we can test.

I thought you readers would really enjoy the rifling twist-rate test I did this year and last. I published 13 parts of that report; and by the end of it all, I was standing alone in my field, listening to the crickets chirp. I also published the entire test in Shotgun News as a feature article and, while the editor got excited along with me, there were more crickets chirping. It’s clear that I don’t always know what will turn your crank.

However, if the comments that came in when I merely mentioned this test was coming are any indication, many of you are very interested. And now you understand what this is.

This gun has a cheap soda-straw barrel (one made from very thin steel tubing). It’s rifled with a compromise rifling that’s good for both lead pellets and steel BBs. The trigger is the same one that’s on the Crosman 2100B that I tested for you. So, expect accuracy like you saw in that test. It wasn’t that bad, as you will see, if you bother to read that report. As for velocity, well, I already know what it is, but I’m not telling today. That will come in Part 2, like it always does.

My goal
The point of this test is to see if a gun can be made this way, and, if it can, how will it perform? I’m not going to tune this rifle to turn it into a viable air rifle, if it isn’t one already. I just want to know if it works. If it does work, does it work good enough that it would be worth building a commercial rifle just like it? In short — is this worthwhile?

I haven’t mentioned numerous things. Things like the fact that larger-diameter tubing could have been used, if the design was altered upstream in the manufacturing process. The cost wouldn’t have been that much more because the alterations would have been made with cost control in mind. Obviously this rifle could also be made as a .22. Is that of interest to anyone? There is a Crosman 2200, you know. A better trigger could be made if there was corporate support for one.

I also haven’t talked about the obvious point that the fill pressure of this gun will be lower than even that of the Benjamin Discovery. Because of that, the wall thickness of the pressure tubing can be much thinner than what’s been used here, meaning a production rifle could hold a lot more air than this one. So, whatever shot count we see here can easily be increased with very little additional cost, if any.

And the valve can be modified by an engineer to work best at the pressure that’s available. The new valve will be different than the one in this test rifle, but it doesn’t need to cost any more money.

In short, I’m testing a concept — not a production air rifle. The final rifle can be so much more than the one I test for you, yet the cost to produce can easily be held in check to ensure that a retail price of less than $100 is entirely possible. I’m tired of being told by airgun companies why something can’t be done, and now Dennis Quackenbush has made it possible that I don’t have to. None of us do.

But this is not a high-quality air rifle that’s made of wood and steel. You can’t build a PCP for under $100 and have those things. This is an air rifle for those guys who want to try out PCPs but don’t want to spend large amounts of money getting them. And also for guys who just don’t have the money to spend — period. That doesn’t mean that it has to be inaccurate — but don’t expect a Lothar Walther barrel. And accept plastic for what it is. You accept it on Glocks — expand your horizons.

This project promises to be quite interesting. It will answer questions I’ve wondered about for close to a decade. Because there’s a real air rifle to test, it will put an end to all the loose discussions and blue-sky dreaming that goes on…because this rifle now exists!

I’ll end with a thought from Dennis. If this rifle is worth making, then a lower-cost hand pump (that would fill only to a lower pressure) would also be extremely good to have. He’s thinking about that one right now.

209 thoughts on “Building the $100 precharged pneumatic air rifle: Part 1

  1. IMO there is a place in the market for a PCP airgun like you describe above. Whether or not it happens is another story. Let’s hope so.

    In other news I saw today Crosman is dropping the Rogue from their PCP lineup.


    • That is not surprising. For about the same price the big bore guys are buying or building more accurate, more powerful and better built air rifles.

      If it had been priced in the $800-$900 range, it might have sold. Now if they were to bring it back out in a more traditional style stock with a 24″-36″ barrel and the price was around $1000 AND the accuracy was shown to be sub 2 MOA, it would likely sell. I might even give it some serious thought.

      I strongly suspect that should the .30 and .357 pellet rifles catch on you will see Crosman bring out some models in those calibers. They may even revisit the Rogue.


  2. Wow I thought the 760 would be better candidate because of solid barrel. But the 2100 has longer barrel which is better for velocity . My guess is its going to get 3 shots at 500 fps with light pellets at 100 psi.


    • “Wow I thought the 760 would be better candidate because of solid barrel.”
      The only problem with that is that the current iteration of the Crosman 760 doesn’t have a rifled barrel. Its a smoothbore which means accuracy deteriorates quickly once you get past 10 meters or so.


      • True I also saw that BB said Dennis was going to do it to 761 but the 2100b just popped up instead. Lets all convince BB to stretch the truth for a joke and post 1600fps with pba ammo with 110 good shots per fill with only 800psi That will get all their attention. HA. HA.


  3. B.B.

    It seems perfectly clear to me that if you achieve velocities of about 700 FPS and maintain the group sizes of the typical 2100B that you have without question achieved your dream of building a worthy PCP rifle that can retail for about $100.00. Thereby making it possible for all to own a PCP rifle that has been until now out of the reach of many airgun enthusiasts and entry level shooters.

    This is a very admirable goal and you are to be applauded for achieving it. Pending of course the results of the velocity and accuracy tests. Good job.

    G&G



    • “What do you think Crosman will say about this? Crosman will reply to notify you have just forfeit(void) the warranty.”

      Which is not a big deal on a $60 air-rifle.


  4. Big corporate Air gun company have a bottom line guy to see how to save money look how just to keep the Benjamin 392 alive they changed the wood .I saw 392/397 selling for $114 at a big chain sporting goods store Crosman web site $160. And RWS Diana instead of fixing barrel droop they made a compensator mount instead was that brilliant. We the consumers want the better quality air guns and well pay the fair price. We are buyin $600 Beeman R1 instead of Marlins 60 proof is in the pudding.


    • +1 In fact, I think if Crosman marketing worked harder to get its PCP guns on the sales floor where people would start learning about them, a lot more would be sold. I have yet to walk into a big box store, outdoors specialty store or gun shop and see a PCP on the rack.


      • Actually, they are starting to show up in these stores. I have seen the Disco and pump set in either Sportsman’s Warehouse or Gander Mountain this past month and Wally World sells this set for $368 online. You just might see them on the shelves soon. You may rest assured the marketeers will do all they can to make a quick buck. Air guns are catching on.


      • Mark,

        The reason you don’t find PCPs in brick and mortar stores is because the salespeople don’t want to learn about them. When I was at AirForce we tried selling to a large store and they couldn’t handle the technology. When we offered to come and train the sales force they told us the turnover rate was too high to sustain the training.

        That is why PCPs don’t usually make it in stores.

        When we designed the Disco, I wanted it to contain its own training, so once the box went out the door the store was finished. Crosman did a lot of what I proposed, including an animation about how the gun operates and a much better owner’s manual, but more still needed to be done.

        B.B.


        • I have a disco and an airforce condor. I don’t see either gun as very hard to operate. However the airforce guns are a bit more technical due to the ability to swap barrels. I found the gun a bit intimidating until I watched the video which by the way was the best way to do an operating manual. Even with the Airforce guns being slightly more complicated than a disco I was up and running with it in about an hour after I opened that black box. That black box is the guy equivalent to that little blue box from tiffany’s that women like.


  5. Years ago 2005 I think Compasseco web site( PA bought out)they offered the QB78/79($89) with a modified HPA reservoir . I don’t think it caught on not sure the cost.


  6. BB, My first air gun was the 2100B in .22cal. I really liked it and found it to be very accurate.I killed many Ground Hogs, Squirrels, a few rabbits and one big Possum with that gun. I would love to have the PCP version of the 2100B in .22cal. Now if only Crosman would wake up and smell the money. Do you think they will?


  7. BB,Capital idea oh wise and learned one! The $60 initial cost includes the profit margin of the manufacturer and one for the retailer too.Now the extra costs of the new parts can be offset by the savings of the parts Dennis discarded and maybe add to a new profit margin for the manufacturer.But the retailer may see the chance for a greater profit margin for themselves and there goes the cost up again.–Another thought;Why do extensive testing on this gun?Shot count and velocity are all that you have influenced.Unless the velocities in the string jump all around,the accuracy should be typical of the original gun.

    It’s a new year coming and the new ideas are flying.I had an idea,maybe a stupid idea,but I hoped you would critique it.Maybe I’ll bring much laughter to the new year.:)Anyway,Take an air tank from a pcp that can accommodate an extension.Manufacture it with a tight fitting piston inside.Put an extra o-ring seal or two on the piston and a lube impregnated band also.Now install a spring behind the piston and a hole behind the spring.Cover the hole for dirt but it must be able to pass air.All this is in the air tank and is installed on the rifle.Now fill the tank.As the tank gets up to pressure the piston moves back and compresses the spring till it bottoms out.A peak in pressure tells the operator to stop filing.In shooting,as the tank pressure falls and the sweet spot in the shot curve would normally fall,the spring pushes the piston to maintain pressure thereby extending the useful shot count.The hole in the back allows for pressure release behind the piston and prevents air loc as it returns.I estimate that the piston movement would be slow and gradual so as to have no effect on the shot cycle vibration and accuracy would not be adversely influenced.–There,am I ready for the loony bin or is this a feasible idea?
    Happy New Year BB,Edith,and all my fellow blog readers.Thank You for another great year in airgunning.-Tin Can Man-


    • Now add this to your idea.

      Fill a rubber bladder full of liquid and put it in the reservoir instead of the spring. Lets talk only one shot per fill like a spring gun or pump gun. Let’s just try 150 psi which is what a normal household compressor will make. Put a tire valve in the end of a tube with a low pressure gage.

      Fill it to a 150 psi. The air will push against the piston which will push against the rubber bladder filled with a liquid and it Will compress. And I ain’t worried about what kind of liquid right now. You know so it don’t freeze or something. Oh wait a minute maybe we can mix some anti-freeze with the water that is in the sealed bladder. We load the projectile. Pull the trigger and the compressed air is released with the compressed bladder with the liquid in it pushing the piston forward.

      Same thing as your every day spring gun I would think. How many pounds of pressure does the spring in a break barrel spring gun make when it pushes that piston?


      • Liquid does NOT compress Which is why pressure testing air tanks is done with water.*

        Shoving a liquid-filled bladder into a reservoir is no different than dropping the same volume of steel BBs into the reservoir — it only takes up space and reduces the volume available for air.

        * Say you have a tank with an inside volume of 1 liter of water. If you fill it with water at 200Bar, you still only have 1 liter of water inside the tank. If the tank ruptures, you get a puddle the size of a spilled milk carton. In contrast, if you had it filled with air, you’d have maybe 200 liters of air when it ruptures, and those 200 liters are going to try to fill the room you are in (IOWs, instead of one milk carton of water on the floor, you have 200 cartons worth of air suddenly appear from a 1 liter bottle).




      • I know but I’m trying to think a different way.

        With the combined idea of Tin Can Mans piston and my bladder filled with a liquid and using the air to basically to compress the piston and bladder. The air is the cocking mechanism.

        All we are doing is lets say taking the guts out of my Diana 54 side lever. And maybe I should use a different gun as a example.

        But I’m now going to put in the bladder with liquid and the piston instead of the spring. The air is going to cock the spring/bladder and piston (not the side lever any more and of course it would have to be a air tight tube with a fill port on the end). And the air will hold the piston and bladder back. The air is acting like a cocking device. But you also get the benefit of the compressed air also going to the transfer port.

        You wouldn’t have a air valve any more that would transfer the air charge. The trigger would release the air all at once form the air chamber just like when you pull the trigger on a spring gun. No air valve. And piston slams forward also as the compressed air is released.

        I don’t know if I’m explaining correct.


    • Tin Can Man,

      Why test the gun? Because it exists. There could be things we might never imagin in our conversations that a test of this gun will reveal.

      As for your PCP with sustained air pressure, it sounds like a sort of reverse regulator. You won’t be able to fill to 3,000 psi, because no firing valve I know of can operate at that pressure. But at 2,000 psi you may have discovered a way to get more shots for the fill. Only way to know for certain is to build one and test it.

      I want the story if you do.

      B.B.


      • Hi BB,

        Tin Can Man’s idea is basically the proof of concept I am working on. It is simple – a tube with a fill port, manual valve port and a piston with a spring behind it. Fill the tube with air (no tension on the spring) then compress the spring after the tube is full. Once the spring is compressed open the manual valve quickly and measure the velocity of a projectile it propels. The energy of the projectile should be a good indicator of the effectiveness of the idea. Basically it is a hybrid pcp/spring piston valve. If the concept proves out, there are many ways it could be implemented.

        Daniel


      • BB,Thanx for looking at my idea and your comment.I won’t be making one as I don’t have tools or equipment ,or money for the job. But I wanted to get the idea off my chest.

        After your answer to why test,I went back to your reports.I couldn’t find a 4th report.You probably haven’t changed the overall weight of the rifle too much ,so it is probably still in the 5lb range , but I’m thinking that you have changed the balance to a muzzle heavy gun.This is (as a rule of thumb) your prefered situation for better accuracy as you have told us in the past.Now I’m anxious for you to show us how it does test out.

        Sam’s point about safety seems valid.However you have shown us that airguners are a small consumer group and upward and downward compatibility is important.I have 3 pcp riles and would get one of these too if my hand pump could work with it,but not if have to get a whole new pump.Many people would want the new,cheaper pump for the rifle if available.But I would look ahead and get the bigger pump if I thought I might ever want to upgrade to another rifle.If I were a new airgunner;after purchasing this rifle and a proprietary fill system I would think twice or three times before buying everything all over again just to upgrade.I probably wouldn’t do it.-You certainly know how to stir the pot.-Tin Can Man-


  8. Well I’m just going to say it the way it is.

    We were shutting things down at work tonight. Almost time to go and do my hour drive home. I always try to peek at the blog so I can see what the topic is for the next day and think about it while I’m driving home.

    I started jumping up and down and I heard myself say Yes! And I don’t do that kind of thing. The other girls and guys looked at me like I was crazy. I said BB did the article about the $100 PCP.

    One thing I can say is cool stuff. But maybe I shouldn’t jump so high just yet. It all sounds fine and dandy.

    But!

    And sometimes physics override thought.

    And here is where I’m going to be a gambling man this time around or fortune teller or something. The gun will shoot a bb or a pellet especially with that type of rifling in the barrel. There will be minimal drag. If its a pellet the skirt on the pellet is not going to expand especially if the air valve releases a lower amount of air for a sustained amount of time its just going to glide down the barrel with minimal resistance.

    And people are going to say yea right it will loose pressure and the air charge will blow by. Well how about those Pea Shooters when you were a kid if you were lucky enough to do that when you were younger. A straw and a pea. They shot the pea like a miniature blow gun. And I may be full of hot air but not a hundred psi of hot air. Think about the blow guns that are available today and get one of those if you get a chance and see how they perform.

    And we make little air guns at work all the time messing around. There not a pcp but they could be real easy. We use our air nozzles we blow our parts off with and put a copper piece of tube on the nozzle and shoot the small diameter steel tumbling media out of them. Our air pressure is about 150 psi at the nozzle. The .125″ dia. by .300″ long media will stick in wood pallets at about 30 ft. Oh no. You heard wrong. I would never do anything like that at work. ;)

    But I can say anything right now and it could sound for real or maybe a bunch of you know what.

    Sorry but the gun will shoot and better than we think. I may eat my words but I’m a gambl’n man tonight. Its going to work. Oh and it will only get one shot per fill. And it will be with a lot lower fill pressure than your thinking. Lower than the Modern day PCP’s.

    Boy I’m going to be the biggest fool on the blog if it don’t work. Oh well wont be the first time I have been wrong. And I will live to try if you know what I mean. This is the stuff I love. At least I will learn something for the next time around when somebody trys something. All I can do is learn.


  9. Hi B.B., I for one would be very interested in a PCP for under $100, though by the time it got to the UK it would be around £130 i would think. I forked out out over £100 for a 1077 a couple of years back and they come with a smooth bore barrel in the UK, so i would have happily spent that money on an accurate plastic PCP instead of of an inaccurate plastic co2 air rifle.

    I do have two fine Air Arms PCP’s that took a lot of time and hard work to save up for, i also have some pretty cheap multi pumps that i really enjoy shooting. So to say you piqued my interest with this project is an understatement, i am looking forward to further installments and what a splendid way to start the New Year. I thank you and Dennis for visualizing this amazing concept and lets hope someone is listening who has the ability to take it up, a Happy New Year to you all.

    TTFN

    Best wishes, Wing Commander Sir Nigel Tetlington-Smythe.


  10. Chirp, chirp, chirp…

    I guess I must be one of the crickets in the field. I may not always comment, but I do always read.

    Your article concerning twist rates has been “reprinted” on other air gun forums also, even one that does not hold you in high esteem. It very likely has been read by quite a few engineers in various air gun companies.

    Yesterday, I was talking to a gentleman who has been interested in air rifles for quite some time now. He has been considering a sproinger such as a Benjamin or Gamo, which are available locally. He has tried a Benjamin sproinger pistol, but did not care for the creepy trigger. He prefers to have a little quality with his money and will pay a little extra for such. I pointed him to PA and recommended a RWS 34 in .22. It will give him a trigger he will like and enough power and accuracy to whet his appetite (he is an avid hunter). If he gets that 34, I imagine he will start looking at PCPs in a year or two.

    The Discovery rocked the air gun world. A decent quality, “low” pressure, reasonably affordable PCP. This is really going to make it rock.

    I would not be surprised if a marketeer in some air gun company walks into work this morning and says “Boss, I have a great idea! Why don’t we build an inexpensive air rifle for under $100?”

    Chirp, chirp, chirp…


  11. By the way, I personally would not be interested in buying this rifle because I know I would not be satisfied with it. However, as you have pointed out, it would be a fantastic place for someone to start. Many who own Air Arms, FXs and such started with Red Ryders.


  12. Maybe the low fill pressure will get their attention also. The lower the fill pressure, the happier the legal department will be.



  13. BB,
    Pardon my ignorance, but does the residual air pressure or a spring close the valve?

    Also, you realize you are going to get the creative juices flowing with the DIY crowd. I myself have already been thinking of a 397/392 PCP. Could my Izzy be converted to PCP also? Hmmm…


  14. An entry level PCP gun for $100? Great idea.

    But you still have to spend $200 for a high pressure pump.

    Not to rain on anyone’s parade, but we’re still talking about $300 to own it.


    • I strongly suspect you will not need that high of a pressure pump with this thing. It could be built to use a lower pressure pump which would be cheaper ore even a standard shop compressor. The Disco only uses 2000 PSI. The old timey air rifles and pistols used 600-800 PSI. CO2 guns use under 1000 PSI.


    • Chasblock,

      Didn’t you read the final comment in the report?

      You are not looking at an offering that’s on the market. You are looking over the shoulders of engineers who are attempting to learn whether this is a good idea. If it is, then there is more to it than just the gun.

      B.B.


  15. I dont know, but, you guys started with a 60 dollar PCP… the fact that you have to pump every shot is inconsequential… a multi pump is in effect a PCP with a pump attached… a disco was already a low price PCP. The fact that is still sold for 260 dollars amazes me. The cost of the disco should be a more palatable 150 to 200 dollars (notice every refurb for 150 dissapears within seconds…)
    I appreciate the workmanship and creativity… but see no point.


  16. Great idea using 2100B. I would buy one at that price but now that we have taken care of the front end we still have to look at the back end-how do we fill it. Will the fill pressure be low enough to be able to fill it from say, a modified “beefed up” bicycle pump or a cheap $99.,125psi compressor. I think that if we can bring it to market for USD 150-160 ( pump included ) it would be a winner.
    The lowly 760,entry level multi pump, which now retails for USD 32 has already sold over 10 million units.
    You can sell 100,000 units @ a profit of $25 each and make $2.5 Million or you can sell 1Million units @ a profit of $10 each and make $10 Million. The choice is ours. The question is- do we have the nuts to make the decision to take only a $10 profit on each gun??
    My idea would be to take a cheap Chinese underlever and turn the piston around turning it into a pump. If you were to place the butt on the ground you can apply quite a lot more force to the pump handle. The Butt would have to be hollowed out to accommodate the air reservoir ( Lewis and Clarke, Air Force and FX guns). Note that I am only addressing the pump and air storage. Dennis will have to apply his expertise to add on the barrel, valve, trigger and all the other parts required- perhaps off the shelf parts from the Disco might work.
    Happy new year to all.

    Pete


  17. Love the idea……
    but no way is Crosman making this gun. They aren’t exactly a forward-thinking, risk-taking type of enterprise. For example, look at the 2240. This thing has been around, what, a gajillion years now, and while every conversion you can think of has been done by the DIYers the Big C has left it virtually untouched.
    They’ve got their “high end” (and stupidly overpriced) Marauder, they’ve got their “entry level” Discovery. Even utilizing an existing platform is still going to cost money for tooling.
    And as has been mentioned, filling is always an issue. I know it kept me from buying a Disco initially-$200 for an oversized bicycle pump is a hard pill to swallow when you’re on a budget.

    I’m afraid it’s all up to you BB!
    Get to work!!


    • DD,

      I’m afraid I have to disagree. It may seem like Crosman moves slow on some things, but as airgun companies go, they are a leader. The Disco and Mauauder (which I think is priced very well) are examples of that.

      I think we are going to have to disagree on this one.

      B.B.



        • Now your talking. I myself wanted the semi-auto feature of the Monsoon.

          But if they made a Monsoon with the on board pump of the Independence I would have to be selling some guns to get that one.

          Fx are you listening?


  18. BB,
    I like the idea. I think 10 to 20 useful shots per fill in the 750 fps range with 7.9 grain pellets would make it viable. I also like the idea of a lower cost hand pump. The fill method start up cost is another barrier to the guy who wants to graduate from springer’s or CO2 power lets to his first PCP but has a low budget. I hope you succeed!


  19. I love the concept of these low cost entry level DIY PCPs, however I would love to see some information included on some of the other things people have been doing, such as HPA setups, and the like. I know some of the airgun forums there is a bunch of talk about the Flying Dragon xs60 based $100 PCP. Any chance of getting a review on one of those bad boys?


  20. Not a lot of time this morning to read all the ins & outs of every response, but a couple of things stand out;
    Overall, beware the enticement of going too cheap…carefully note the use of the word “cheap.” What happens in the retail venue, in the final analysis, is the only thing that matters. If the buying public’s perception is that the item at hand is so inexpensive as to be “cheap” you’ll never sell enough of them to make the tooling costs back. You’ll also generate an economic situation that discourages not only initial investment interest but the further investor patience with the normal dynamic of new product introduction. In other words, there will be a strong incentive for investors to “pull the plug” too soon before the new product has a chance to establish itself.
    It appears the rifle itself is not the crucial component, but rather the recharging apparatus, whatever that may be. The buying public is not going to spend $100 on the the rifle, and then however much more on a scuba tank kit…nor even, what? More than the the item at hand for a $100-$200 glorified hand-pump? Doubt that
    Neither are they going to accept a one-shot-per-charge rate.
    Still, interesting ideas with much merit.


  21. Happy New Year to all,I hope it’s a better year than 2013,I read the blog twice, and now I think that
    there could be a market for it,and I wish that one could use a less expensive compressor than the
    $1,000.00 and up it could bring more people into the pcp field and possibly Major Manufacturers
    might take up the mantra and commercialy build one.I don’t expect British or German Quality”
    You get what you pay for”I was put off for years from purchasing a pcp because of the inconvience
    of filling at a Scuba station or the constantly refilling the portable tanks even when there is still
    1500 psi left in tank.
    I think 103 David is right, Only when you can fill a cheaper pcp with a standard compressor will there
    be a market for one.Who wants to spend $200.00 or more for a hand pump for a $100.00 rifle I believe
    will not last very long even after moderate use.


  22. Actually I just bought a 100 dollar PCP. I found a brand new Discovery in the box with pump and the retailer sold it to me for a hundred. It had sat on the shelf for over two years with no takers at the $299 asking price. For many Americans air guns are still seen as toys. We all owe a huge debt of gratitude to Tom G. and the handful of others who are changing this by making very high quality air rifles affordable.
    There was a guy in the store when I bought the Disco who asked if it was one of the new air rifles that it was legal to hunt deer with. I told him that deer hunting with a .177 rifle was not a great idea. He immediately lost what little interest he had in the Disco. So if the new rifle is accurate it has potential, but it is tough to break the commodity mindset. Sell grandma for a nickel! It is a wonder that low end air rifles have rifled barrels at all considering the pressure of the marketplace to keep prices very low. The next challenge will be to get Wal-mart to actually stock a decent pellet. As Tom has pointed out a few hundred times a great rifle with cheap pellets shoots like a cheap rifle. This is also part of the reason that high quality air rifles do not sell. A shooter buys a more expensive rifle and gets little accuracy improvement over the old Daisy until he buys good domed pellets online. So in the minds of many shooters air rifles are only good for plinking at cans.



      • Thanks to you Mr. P. for chaining my perception of air rifles and making me realize why great deal this was. The retailer actually had a dusty brand new Discovery on the shelf. The clerk called the manager to ask about the price. The manager said sell for a hundred. The clerk then found brand new in box in the back that was not even dusty. So I conclude that the market for higher priced air rifles in the US is still limited, but does that mean that cheaper is the way to go? Perhaps there is a market for higher quality. Imagine if Crossman sold the 397 with a walnut monte clark stock, all in polished brass, with a factory aperture sight and a decent muzzle crown free of coating. Would it sell as the Benjamin Legacy model? Probably not, but I’d like one.


        • ray,

          Benjamin already did try to sell a super-duper highly polished brass version of the 392. It was called the county gun and one was supposed to be made for each county in the U.S. That would have been over 6,000 guns. The price was over $300, as I recall (in the 1980s!) and they didn’t sell half of what had been planned. So the rest were not linked to counties and were sold off at a loss. They still pop up in new condition at airgun shows.

          B.B.



  23. This article and the proof of concept gun being built is an eye opener for me. I didn’t think a pcp could be built that retailed for $100.

    I believe there is a large market for this gun BUT agree with Dennis that it would have to include pump and I believe the package would have to sell for significantly less than the Crosman Discovery. If the market value of the Crosman Discovery plus pump has settled around $370 I think the $100 pcp would have to be packaged with a pump and retail for around $200 to be successful.

    The folks on this blog are not the potential buyers of this package deal that would include a $100 pcp.

    The market is the next tier down from the Crosman Discovery.

    I don’t have hard numbers but am convinced that the Crosman Discovery introduced more people to the world of pcp’s than any gun before or since. This $100 pcp along with a newly designed pump and sold in a package for $200 is a no brainer. It would be the pcp equivalent of the bronco.

    kevin


  24. I love the idea of a cheaper pcp but there are a few things that I think will stop it from happening. For one thing you would have to have a proprietary fill valve if the entire gun could not stand 3000+ psi. In an age when you can sue for hot coffee or ladders that slip on wet grass there would have to be a way to stop from overcharging. With a small reservoir the gun will need to operate on something more than co2 pressure to get any number of shots. This gun would be a direct competitor to co2 with 2x-3x the entry cost. Although WE are all a bit nutty about a new gun there are not 1,000,000 of us, the majority of these would be sold to parents for little johnny who does not understand about dirt and dust in valves and pumps so warranty returns would be massive and johnny would have to be able to pump it up himself. Or it would be considered too complicated for a 12 year old and passed over in favor of something cheaper and simpler. You also loose the variable power the pump gives. And finally I know I am probably alone here but while I will spend a little money on a throw away out of curiosity or a lot of money on quality that stands the test of time I will not spend allot on throw away curiosities. Of course I still use a 6 year old flip phone because the voice quality is good and battery lasts forever while my son in law has to have a new $400 dollar phone every year because the processor is now faster and camera pixels have increased another 6 meg.



      • Well you can get a co2 gun for $50 but the entry cost of the pcp is the gun and a pump. Even if the pump is dirt cheap it will be another $100. So thats $65 to $100 for a BB/pellet rifle. If you want high quality you will need more of a base than a 2100.


  25. Tom, I have a question. If major companies don’t show any interest in the $100 PCP, I don’t suppose you could put a detailed how to (either video or text w/ pictures) on the conversion up so that us less technically gifted people who are interested in one could build it themselves if they were so inclined.

    As for fill pressures… I’m a little curious what you used myself.


    • J.,

      The technically gifted already know how to build this gun. And trying to do it as a DIY project could risk some serious injurys, so I’m not going to show how it was done.

      I will address fill pressure in depth in Part 2 of the report.

      B.B.


      • “The technically gifted already know how to build this gun. And trying to do it as a DIY project could risk some serious injurys, so I’m not going to show how it was done.”

        Fair enough. I could make a counter to that argument, but I understand where you’re coming from so I’ll leave that particular sleeping dog alone. Though the fact that there isn’t a simple way for non-technically gifted individuals to do this sort of conversion sort of makes the question of whether one of the big companies will ever offer a $100 PCP a bit more important.


        • J.,

          I wasn’t trying to sound snippy with my answer, but it did come across that way. What I meant is, those who are hobby machinists already will look at this and instantly know how to build it. They might deviate from exactly what Dennis did, but the results would be similar.

          B.B.


          • Those who know how, may have already started one. I started building one earlier in Dec. and almost have the tube completed. It will be shooting in another week.


          • “I wasn’t trying to sound snippy with my answer, but it did come across that way. What I meant is, those who are hobby machinists already will look at this and instantly know how to build it. They might deviate from exactly what Dennis did, but the results would be similar.”

            Tom first things first… I didn’t think you sounded especially snippy. And as I said in my previous response I understand why you don’t want to release detailed how-to instructions: liability concerns if someone botches the conversion and gets hurt. After all the air in PCPs is compressed to fairly high levels and if the conversion isn’t done right it could pop like a balloon that’s been over-filled with correspondingly negative results.

            Since you’ve already poked the sleeping dog with your response a bit though… I think you have one minor error in how you’re seeing this. You’re seeing 2 groups: hobby machinists who instantly know they can do the conversion (and how to do it) and everyone else who can’t. I think there are actually three groups: hobby machinists who instantly know they can do the conversion (and how to do it); those of us who don’t know instantly how to do it but are smart enough that we could probably follow detailed instructions/install a pre-made conversion kit; and those who don’t know how to do it, don’t know that they don’t know, decide that you’ve already told them how to do the conversion, and go tearing off to make their own PCP. Its the last group who do things like make Youtube videos about making PCPs with 2-liter soda bottles for a pressure vessel by the way… and who are the ones likely to things like decide substituting cheap mild steel tubing (or PVC pipe) from the local hardware store for SAE 1026 tubing is a perfectly acceptable option (with the predictable results when they try to pressurize the gun). That’s just my take on it though.


  26. I love this idea, regardless of its commercial viability, and really look forward to the series.

    Set learning mode “on”*, and absorb.

    _____________
    * Who am I kidding? The minute that mode goes “off” might pass muster as a clinical definition of death. :-)


  27. BB,

    “the sound of crickets chirping” is actually a good sound. It’s the sound of a huge meal being digested in peace. I got a lot to think about and absorb with your twist series. I’m still digesting…

    Kinda thought you might start with a base Crosman gun. I wonder if you could seal the barrel sleeve, make a passage and use it as extra reservoir capacity? That might put you over the magic $100, but not by much…

    /Dave


  28. Wow. I am inspired by your inspiration. Thank you for turning my very first airgun into what might be my very first PCP. The 2100 fantastic. The groups you were able to get with the barracuda greens were very impressive. I will look forward to seeing how this one shoots. Is this the same 2100 tested earlier? Mr. Quackenbush is awesome.

    Your report on accuracy/velocity as compared to twist rate was fascinating. More good information for the people who make our guns to consider.

    With what you mentioned in crosman’s abilities to create a much more cost-efficient gun with a larger air supply, I am very excited. Thank you Tom. Thank you Dennis.


  29. B.B.

    I like where you are trying to go…. I have to agree that there is a market for a mediocre accuracy air gun… with only the ability to hit tin cans at 20 yards.. and maybe 1-2″ groups at that distance with good pellets.. There are a lot of folks that would enjoy that activity with their kids or grandkids.

    I disagree with those that say the filling system is a major problem… I don’t think there is a problem with paying more for a filling system like a pump or scuba tank, than the rifle itself… when one considers the cost over time of CO2 cartridges.. cause that is the market you’ll be taking from initially. “New to air gunning” customers have to be courted… but this would be a great item to do the courting with:-)

    I believe you can have a fill pressure of as little as 1,200psi and shoot from that down to about 800psi and get 20 good shots at about 12 to 15 fpe … and that will help to differentiate it from the Disco at another level than just price.

    Just think how many fills you could get from a scuba tank with a fill pressure of only 1,200 psi! You wouldn’t be making the trip to the dive shop very often.. and your cost per shot would be so low! That is why folks will be willingly to pay more for the fill system than the rifle itself.

    I don’t find the Disco that accurate, with the flimsy low cost barrel… and the trigger is not to my liking.. but at that price point, it works for lots of folks, and I like mine just fine for starlings and the like… just not for a field target shooter on a serious level. .. but it’s fine as a starter in the game, and doubles greatly as an all around plinker.

    But, the Marauder IS a serious FT air rifle… and it’s a very good next step above the Disco… so an air rifle below the Disco, to me makes perfect sense… and some dollars too:-) for any manufacture who can make it.

    Happy New Year All!!

    Wayne Burns,
    Match Director,
    Ashland Air Rifle Range,
    Ashland, Oregon.. come on down and play any Saturday!


    • “I like where you are trying to go…. I have to agree that there is a market for a mediocre accuracy air gun… with only the ability to hit tin cans at 20 yards.. and maybe 1-2″ groups at that distance with good pellets.. There are a lot of folks that would enjoy that activity with their kids or grandkids.”
      How about enjoying it alone? ;-) I love plinking and shooting cans.
      It’s where most of my shooting is done as I don’t hunt or compete. I have a sub .25 inch PCP rifle for precision fun, I used to have a FAS 604 target pistol that I sold because I needed the money and frankly I just wasn’t using it. So PCP plinker? Bring it on!

      Backyard competition, family gathering and BBQ’s at the cottage during the summer, bring out 2 or 3 of those and you have every guy hooked for the evening. I don’t even need super fast velocity (especially since I’m in Canada and I don’t want to bother with a license and registration), shot count would be more important to me.

      I totally agree with you on the working pressure and filling from a scuba tank. Not only would you get a LOT of fills you wouldn’t need a high end (expensive) carbon fiber tank, any used 3000psi diving tank which can be found for less than 100$ would be the ticket to lots of cheap fills!

      People are always asking for a better mouse trap, we have one right here and it’s cheap too! Build it!

      I’m really happy this got published today because I didn’t want to wait for the week-end to have it published but the number of comments tells me this is a friday blog ;-)

      J-F



  30. That’s what the M4-177 and MK-177 should have been!!! THAT I would have bought in an instant.
    I’d love a PCP plinker. There’s a place for plinker gun especially if they look like some of the available firearm. Not everyone wants to hunt or target shoot.
    Just look at how many people are bulk filling their CO2 repeaters, those kits cost around 50$ over the 100$ rifle price. Just make it a low fill pressure PCP for a 100$ and you’re ahead 50$.

    A lot of airgunnners already have the filling equipment so it becomes super easy to refill or even better make it dual fuel like the Disco, you have the equipment refill it with air, you don’t fill it up with CO2.

    A BB PCP repeater would be cool IMHO.

    J-F


    • “I’d love a PCP plinker”

      That is exactly why I bought the $100 Flying Dragon PCP. I have a Marauder, and a RWS54 – but I wanted a simple, inexpensive open sights PCP for plinking around in the yard. The fact that it fills to 1500psi makes that even more attractive as a plinker as pumping will be easy. I believe it has the capacity to run off C02 as well – since that is what the original base XS60C did.

      For $100 SHIPPED! I figured it was worth it, and I am guessing it will be a gun I grab more often than not.


      • I just checked the Flying Dragon web site and their cheapest pcp is listed as $209.95 including shipping. Where did you get yours for $100?

        G&G


        • G&G,

          I’d like to know too. The model that eric lists is shown as a co2 gun costing $129. Is he getting something else from somewhere else? Spoof site or ??

          /Dave



          • Found it. Thanks, but it looks like a limited run special, not a standard “you can get this any day” product. I don’t need one so I’ll let others enjoy!

            /Dave


            • Correct, the stuff Mike makes is custom built. So the quackenbush hack gun BB talks about in this post.

              That said, the rifle Mike has just started custom making is much higher quality.

              Mike makes them custom to order I believe, but you can just email him and he will make it. That is what I did today.


              • Eric,

                Woah, pardner! Hack gun? Are you not reading this report in full? This is a proof of concept — not a finished product. This is a testbed gun. I probably said that 5 different ways in the report.

                You don’t have to demean someone to make a point on this blog. I am talking to Mike about his rifle, but let’s refrain from denigrating someone who has unselfishly given his time and money so we could look at a concept.

                B.B.


                • I didn’t mean “hack” in a bad way. For me a hack is exactly that, a proof of concept, or some thing some one worked up to demonstrate a concept. Not a refined general solution. Hacking is a good thing, if people didn’t hack stuff we wouldn’t get new and innovative things.

                  I certainly meant no disrespect to Dennis Quackenbush at all. Sorry if the meaning came across the wrong way.


      • A cheap plinking pcp would go along very well with my Steel Force.

        I personaly hate pump guns, pump-pump-pump-pump-pump-pump-POW, pump-pump-pump-pump-pump-pump-POW. Just isn’t worth it to me, call me lazy if you want.
        For me shooting is a pass time, it has to be fun and pumping more than 3 times between shots isn’t my vision of fun.
        I know some people love them, the total lack of recoil is nice, the self contained part too but it’s just not my bag of tea. I tried HARD to love them, from a 1377 and 760 up the nicer wood and metal Benjamin HB pistol and 39X rifle… but it’s not for me, I only kept two old 2289, I got rid of all others.

        J-F


        • I completely agree. I find pumping between shots to be distracting and irritating. I also tried very hard to like the 1377, even bought a wood grip and pumper forearm but still just couldn’t get into it.

          G&G


        • That’s one reason I’d like to see more low-cost, single-pump pneumatics. Especially one sized for an adult. As far as I know, Daisy’s the only player in that game and their least expensive model is the Daisy 840 which is sized for little kids. (I’m not sure how the Daisy 953 is sized, but its not exactly what I’d consider inexpensive. To be fair though I’m a tightwad when it comes to money…)



  31. I also just ordered the Flying Dragon PCP air rifle.

    Mike Melick does fantastic work and really considers the consumer in pretty much all of his endeavors and his work on a low cost PCP is just one more piece of evidence to support that.

    It looks like Mike has already answered your question BB, can a $100 PCP be made and will it work? … yes.

    Beyond that, the Flying Dragon PCP is a low pressure (1500 psi) gun that will make it easy for newcomers to the PCP world to get started.

    I would suggest a follow up blog post to this series where you actually test one of Mike’s Flying Dragon PCP’s.


  32. Mr. BB, Ms. Edith & the Gang, Happy New Year. I show up to school every day, sit in the back, keep my ears/eyes open & mouth shut, reading everything written by all of you, I’ve learned alot & I thank you. When Mr. BB first mentioned this rifle he also mentioned showing us something many of us already have. Hmmm, maybe something related to filling it?
    Open OT question to all as anyone who knows which end of the gun the pellet comes out of is a far more experienced shooter than me. Currently pellet testing the T-reX (Thanx again, Mr. BB/Super Enabler). Using several different pellets, shoot each one for a group 3x then average the 3 groups. Good/dumb idea, please?
    Again Happy New Year & THANX to ya’ll.
    Shoot/ride safe,
    Beaz


    • Beazer,

      You are getting confused with what I said. I said there is a new product coming out at SHOT that some of you will already have. That was different from this gun. I never said anyone has one of these.

      Your group averaging method is the way many gun writer do their tests. Good idea.

      B.B.


  33. Since we’re talking about lower pressures anyway,, why not, as has just been suggested, use CO2? The thought about the cost of the small CO2 containers is, of course, valid,, but since this is an “entry level” airgun,, the vast majority will only be shot infrequently after the novelty wears off. Those who continue to have the desire, will be the ones most likely to want to “move up” anyway. Don’t for a minute think that the parents who will be buying most of these guns as gifts to their children, will not understand how quickly old gifts are superseded by the new.

    I will be quite interested in seeing the velocity tests in this new DQ invention. For some reason, I foresee the speeds decreasing with each shot, as the pressure in the reservoir decreases. After all,, the valve used was designed to have the same pressure behind it each time,, depending on the number of pumps.

    I was also thinking about another column I would like to read, concerning a comparison of the velocities and accuracies between using HPA and CO2 in the same gun,, say a Marauder. I don’t know if one has already been done,, and if it has,, I would love a link to it.

    An interesting idea,, but, in truth,, building a $100 pump capable of producing 3000# fills would have appealed to me more.
    Ed


  34. I am looking forward to your coming articles and testing of this air gun. I am a fan of the Crosman 2100B and have owned and shot it’s twin, the Remington Airmaster 77 for like 6 years. It has been 100% reliable and is one of my most accurate air rifles. Tiny one hole groups at 10n yards from a rest with a decent scope are quite common. Even with my 60 year old less than optimal eyesight. The fine readers above who suggested the Crosman 760 would be a better starting gun, I believe, are wrong on that. Not just because of the smooth bore barrel. The 760 is a totally plastic gun, whereas the 2100B has a metal receiver at least. And, by the way, my Airmaster LOVES the common Crosman Premier Hollow Point pellets. Also RWS Hobby’s, Gama Match and other easy on the wallet pellets. My Airmaster is just shy in accuracy to my Crosman Custom Shop CO2 carbine, and maybe slightly better than my Crosman 1077, which is showing itself to be a tack driver despite the trigger.
    A PCP 2100B would be a great air rifle for someone on a tight budget (“cheap”) like myself.


  35. Here is what I’m talking about if this link works with the animation. Is about a bladder. Probably it would be like a gas ram like Pop’s SLR said.

    I would use compressed air to push against a piston that would push hydraulics into the accumulator. But yes its based on a gas ram if you will. All the air preasure does is act like the mechanical cocking linkage.

    http://www.epa.gov/otaq/technology/research/accumulator.htm



      • And remember what a PCP stands for. Recharged Pneumatic.

        Well that’s what I turned the spring gun into when I took the steel spring out. We are not talking about a efficient design of a $100 PCP. We are just talking about what could be involved in making one.


        • I messed on the spelling again.

          “And remember what a PCP stands for. Recharged Pneumatic”

          Should be. And remember what a PCP stands for. (Precharged) Pneumatic.


    • As soon as you add any gas to the other end of the system (the air you state will be used to push the fluid into the accumulator to compress the bladder) you again will find that the accumulator will not compress until the air on the other side matches the pressure in the bladder. You gain nothing but a smaller amount of usable air for repeat shots.

      Hydraulic accumulators only function when the working fluid is a non-compressible liquid. (The reason for the bladder is to keep the pressurized


      • Ok this is what I’m talking about. Basically a nitro piston. I’m not talking about using the air that I compress in front of the nitro piston to shoot out of the barrel. All I want to do is have enough air pressure to cock that nitro piston back. How ever much force that would be. Lets just say it takes 30 lbs to cock the nitro piston with the leverage of the cocking system. So I’m sure you would need alot more air only to compress the nitro piston.

        So if I fill the air reservoir that is the length of the gun to 2000 psi. Release enough air to compress the nitro piston each time or only one time. I’m not going to use any part of the air that is in the reservoir to fire the gun. Only to cock the nitro piston. So now when I pull the trigger it will release the air out that is in front of the nitro piston out into the shroud lets say or the open atmosphere. So now the nitro piston can do its normal job. It can move and compress air with its piston and send air to the barrel and that air fires the pellet as normal. I hope more clear this time. It is 2 different systems working together.

        I think I may have been using the wrong things (a bladder to explain the system I’m talking about)

        http://www.industrialgassprings.com/uk/calculate_basics.asp


        • You are still talking about using one compressible gas to compress a second compressible gas, and that second gas is already starting at fairly high pressure.

          Ah — that link does suggest why most guns using gas springs make the larger shell the moving mass, rather than the shaft… Since most people cock the gun starting muzzle upward, the sealant oil would rest at the shaft seal, rather than on the internal piston head.

          The 30-40lbs “cocking force” is a misleading measure as that goes through a number of levers; the arc may span 18+ inches for a mere 6 inch piston stroke. I’m not sure of the dimensions of the units used in airguns, but presuming 3/4″ diameter one has a piston surface of .44 in^2, and a strut with an internal pressure of 2000psi compressed is providing 883 pounds on the piston. I don’t know the force advantage of the levers — if the peak advantage comes to 20:1, then this would be about a 40lb cocking force.

          To cock this thing with an air source, you will need to provide enough air to fill the “open” end — for a 6 inch stroke, that means you need enough air to fill a .44×6″ (close to 3 cubic inches) at a pressure slightly higher than the cocked pressure of the unit (to allow for parasitic losses). Say the source reservoir is 12 inches long and the same diameter. When you open the valve you create a joint reservoir 18 inches long, and you need just over 2000PSI in that 18 inch volume… That implies the 12 inch reservoir had to start just over 3000PSI.

          You would get just ONE cocking cycle out of that. After cocking, and the valve closes, the 12″ reservoir is down to just 2000PSI. And you imply you will then bleed out the 2000PSI air from the piston-side of the valve to leave the strut latched with 2000PSI behind it. Open the valve to cock a second time, and the residual pressure is now down to around 1400PSI.


          • Wulfraed thanks. That is where I was having the problem figuring this out. How much psi would make enough torque to cock the nitro piston.

            And I think I was explaining this part incorrect. The nitro piston is in a chamber in the tube separated from the air pressure chamber that transfers the air to the barrel. Once you push the nitro piston forward against a a stop its locked in place by the compressed air pressure. So now you pull the trigger and the sear releases the plunger so the nitro piston only does its normal job of transferring air to the barrel. The nitro piston doesn’t move. Only the plunger goes forward. And this way you wouldn’t have to worry about how the fps progressively changes on our modern day PCP guns. the nitro piston could be more consistant in a sense.

            The air bleed would be in-between the the compressed air chamber valve to let air bleed out so you could push the spring or nitro piston back to latch the trigger mechanism. You would then close the air bleed and pressurize the air chamber to cock the spring or nitro piston. At that point load the pellet in the barrel and shoot.

            I wonder if a nitro piston could be scaled down so it could be easier to cock and still have enough power on the air transfer side to make maybe 350 or 400 fps and maybe get 3 cocks from the high pressure compressed air chamber side.

            Hopefully I’m explaining this right. And I would really like to know if the scaled down version could be a possibility.


            • An actual sketch of the proposal would help…

              If you are talking about using some sort of linkage (a pneumatic cylinder, say) actuating the regular cocking linkage, you have to remember that the linkage translates low-force LONG STROKE for high force SHORT STROKE.

              A long stroke cylinder may be operating on pressures only a bit higher than a shop compressor — but it will do so using an air volume that is massive. Put a cylinder with a piston covering 5 square inches (a 2.5″ diameter cylinder) with 120PSI pushing a skinny rod could support 600lbs on the piston shaft. You still need a lever that multiplies that by 3-4X to get to the internal pressure of the strut at full cock. That translates to 3-4X the stroke length of the strut… In my assumption of a 6″ stroke, that means a pneumatic cylinder of 18-24 inches stroke — located some distance to the side, 2.5″ diameter…

              Let’s see if I can describe a simpler mechanism. A simple lever with pivot at one end, the “nitro piston” 6 inches from the pivot, and a pneumatic tube 12″ from the pivot.

              o—|—|

              Moving the strut 6″ vertically requires moving the pneumatic tube 12″ — the pneumatic tube needs half the force of the strut (I didn’t say pressure as the “force” on the shaft is dependent on the pressure AND the surface area being driven against the pressure; as computed earlier, a 3/4″ diameter surface is around 800lbs at 2000PSI) but the same volume of air (1 cubic inch at 2000PSI vs 2 cubic inch at 1000PSI)

              NOTE: I’m perfectly willing for someone else to jump in with better math; all this discussion has been based on 40 year old high school physics…


  36. Merry Christmas and Happy New Year, folks!

    B.B., fascinating article today. Thanks to you and Dennis for making this happen! While the rest of us are talking and bench racing, guys like you are getting the job done!

    I think the 2100B-based PCP is absolutely brilliant. At that price point, I have no problems with the plastic and the quality of the other materials. I still have a soft spot for the old, cheapo MSPs (though I’m a Daisy 880 guy, myself), and I’m pretty sure I would like one in PCP trim just the same!

    One possible benefit of starting with something like the 2100B that might not have been mentioned yet: I imagine the result is one of the lightest-weight PCPs yet made. Such a thing could be the world’s first out-of-box-kid-friendly PCP! If you get a chance, B.B., could you comment on the weight and balance of the prototype?

    For those of us who might like to spoil our kids with a PCP-based plinker don’t have a lot of easy options, at least that I’m aware of. Cut down the stock on a 5- or 6-pounder like the Disco or S200? Marauder pistol? The 2100B seems to suit my 10-year-old better than the Discovery. Maybe the PCPified version would, too!

    Thanks,
    Jan


  37. And BB your right. I hope somebody out there important gets wind of this blog. Maybe it will show that air gunners are serious about their hobby/sport.

    And the things I’m talking about are just ideas. But maybe somebody that knows more about this stuff than I do and incorporate the ideas into something that is already proven. Ain’t that how discovery’s are made. And I’m not talking about the Discovery rifle that you invented.(although good name for the rifle)

    Ideas and experiments being tried from experienced people has to happen. And how many trys does it take when the scientists are try to make a cure for medical problems. Somebody has to try the ideas even if they seem like they wont work when they are talked about.

    What about kinetic energy. How about a gyroscope with magnets placed in certain places. Give it a spin and it keeps going. Maybe it would need a electrical charge to keep it going. And maybe it generate its own electric from the magnets. And I’m just making this up right now.I don’t have any idea if it will work.

    RidgeRunner my turn. HELP! I’m rambling again.


  38. Now this is the kind of innovation that excites me. Yeah it’s done on an old design but I’d deal with the plastic and all ‘if it was built in the u.s.a.”. I’d definitely buy one or more of these, try it out and then rack it with all the rest. It may or may not be an accurate gun, but when I see something innovative like this I’m going to be all over it with few exceptions to the rule. Hell, I bought a gamo shotgun when they came out. I had never seen something like it. I still have it and it does have an interesting history. I bought a whisper when it was new and innovative. I still have that too. I still have both of my crosman m417′s. I was all over that. It was new and exciting despite being all plastic, but it is made here in the U.S.A. I don’t just collect top end stuff. I collect stuff I haven’t seen before and this certainly qualifies. I’ve only ever held back on certain rifles when several reviewers have reviewed it and called it junk and showed it as such. I demand proof a gun is junk before I agree. So Even though I would buy this purely for the innovation I do want to see how it performs.



  39. BB,

    Quite a popular topic!

    This goes back to my old question: Why are PCP guns the most expensive variety, when they ought to be the lowest-priced? They have the simplest construction, the fewest parts, and the fewest moving parts. Yet the most complex, most parts and most moving parts guns (multipump pneumatices) are the lowest priced?

    All pneumatic guns have a great advantage over spring-pistons guns: no recoil. Looking at it that way, the best overall design would be a single-stroke pneumatic. Low power would be the drawback there.

    I’ve never shot a PCP gun. The cost of the gun and its support equipment is too much for me. But I might try one if I could buy it for $100. The cost of the support equipment is still prohibitive.

    If a guy wanted to shoot PCP as a major endeavor, he would do well to buy a scuba tank. But then the cost of shooting a PCP would go way up, unless he bought several PCP guns and spread the cost of the tank between them. And if one wanted to be a “real” PCP shooter, would they even want a $100 gun?

    To go with a hand pump sort of defeats the idea behind a PCP. If you are going to have to pump the gun up by hand anyway, why not just get a multipump pneumatic gun and not have to carry a pump around with you?

    The big advantage I can see with PCP, aside from no recoil, is the ability to fire multiple shots without having to fill the reservoir after every shot. I think other than a PCP gun, only a CO2 gun can do that. Then again, maybe a CO2 gun is really a type of PCP gun.

    Les


    • Les,

      I can see you have been thinking about this one. You bring up some good points that I will address.

      I view airgun design like mountain climbing. When you boost yourself up higher on the mountain, you insert a nut in a crack or hammer in a piton and make yourself fast to that. Then you never have to climb that part of the mountain again.

      Similarly, if a PCP can be built for $100, then I see no reason why it can’t also become an accurate PCP at no cost increase. Once we get it to work we would be fools if we didn’t then make sure it was accurate.

      Your comment about having the pump onboard always comes up at this point. But a good PCP will get 20-30 shots per fill, where a good multi-pump that can shoot more than one shot per charge will only get about 5-10 good shots. The extra volume that the pump mechanism take up is better used for air storage. That why a separate pump is a good thing. As long as the fill pressure is low enough that it isn’t too difficult to fill the gun with a pump, then that is the best way. No scuba tank to lug around and many times the shots as even a top-flight multi-pump can generate.

      You say you have never shot a PCP? If you have shot a Ruger 10/22 or any repeating rimfire then you have come pretty close to shooting a PCP. And, like you mentioned, a CO2 rifle is very much like a PCP. It isn’t as different as you might imagine.

      The support cost is still the biggest barrier. I know something about that, but I can’t tell you until sometime in January. But the support cost can be justified for many more people than currently think it can. Still, it is the biggest barrier there is.

      Why are PCP{s the most expensive, when they are the simplest? Because of the quality that’s put into them., The Benjamin Discovery was a world-beater when it first came out, because it showed everybody that quality didn’t have to cost that much. Remember when I shot half-inch groups at 50 yards with both calibers of Discoverys? If not, then I need to remind you that I did. Some people say they don’t have good barrels, but I think they do. I have a Discovery project about to kick off real soon, so we’ll get to see it in action once more.

      B.B.


      • “Similarly, if a PCP can be built for $100, then I see no reason why it can’t also become an accurate PCP at no cost increase. Once we get it to work we would be fools if we didn’t then make sure it was accurate.”

        That’s why I said the Crosman custom shop would be ideal for a similar platerform. You can get the base model (like the 2240) for under 100$ but you can make a custom one that can end up costing a few hundred.
        4 stocks (Synthetic, folding, beech, walnut), choice of barrel (caliber, length, quality so you can get a LW if you want), repeater or single shot, high velocity or high shot count, etc…

        J-F


      • BB,

        I have indeed shot .22 semi-autos, including the 10/22. I can see where they would be like shooting a PCP. Also several CO2 pistols.

        The big drawback of CO2 guns in my area is cold temperatures.

        If you’ve found a work-around for support equipment, I really am looking forward to seeing it. Since the $100 gun would probably be purchased by people new to PCP, it would make sense to market the charging device as a kit with the gun. For around $200, it could sell to the market just above entry-level springers.

        I want to wish you and Edith, and the blog readers a happy New Year! And thank you for this blog.

        Les


  40. Hello Fellow Airgunners
    BB, you have given us food for thought on this last blog for 2013. I will really enjoy the testing of this $100.00 PCP airgun. I must say, although I find the concept intriguing, I do prefer a few “extras” such as real wood, adjustable iron sights, etc. Items I deem necessary in adding to my enjoyment of airguns. Man /woman does not live by bread alone.
    A BIG Happy New Year to all on this blog. All the best for 2014. ;-)


  41. B.B.,

    An interesting idea, and I suspect you have innovative ideas for the pump, too. I look forward to reading more about this project. Who knows where this might go? 2014 looks promising!

    Happy New Year to All!

    RB


  42. I bet you BB can pick a few guns on this blog ,go to the Crosman company browse thru their inventory and put together a $100 pcp in 1 day.(that’s probably not possible its all made outside of USA).


  43. Hello BB:

    Happy New Year!

    I saw that you mentioned Glock in your blog and wanted to let you know that the manufacturing cost of a Glock pistol is under $100, (might be even less expensive now that Glock is also produced in the US), so why don’t they just sell them for $150-$200?…They cost around $500-$600. Why? Because they are adding the costs of R&D, marketing, advertisements, distribuition, etc…The same principle applies to the $100 pcp gun, it is just not lucrative for Crosman.



    • Costa Rica Kevin,

      Welcome to the blog!

      I know Crosman needs to make money on everything they make, but they can do it on the 2100B, so if the PCP costs no more to build, why not on that, as well?

      No, the issue is will a $100 PCP cut into the sales of any of their existing lines, or will it help them? That is something they look at with each new product. If this gun were to cut the Discovery sales in half, it probably wouldn’t be worth it. But if this one did that but also sold in the hundreds of thousands, it definitely would be worth it. That’s the thinking they do before making a decision to introduce a new product.

      Happy New Year,

      B.B.


    • The parts and machining for a Glock may be that low in quantity… But all of them still have to undergo proof firing, and possibly some hand fitting of some parts… And a final function/target check to see where it prints… Even half a day of a $50/hour technician is going to bump that by $200 (and remember, for a company, if the employee is getting $50/hour in pay, there is probably another $50/hour worth of overhead to cover building rent, equipment, insurance, company half of Social Security.


  44. Hi all. I’m new to all things air gun related after a lifetime with firearms. What I don’t know can fill volumes. I see all these break barrel springers in the FPS arms race and wonder if that technology could be the ‘pump’ you’re looking for. I’m picturing a bullpup design with a side lever to compress the spring or gas ram. You ‘fire’ the mechanism into a high pressure reservoir through a one way valve. Perhaps do this twice. What would you be able to get the reservoir pressure up to? Load pellet into chamber and close bolt (probe?). Triggering mechanism would be an electronic pressure pad connected to an electro valve to release reservoir pressure into barrel to propel the pellet. Costs should be able to be able to held fairly low. You don’t need a strong barrel to be the spring lever. Therefore B.B.’s soda straw barrel can be utilized (with an appropriate plastic shroud) The spring/gas ram/cylinder/seal technology is a well worn path. The spring compression/decompression cycle all takes place prior to the actual pellet firing, so no need to learn the ‘artillery hold’ and dealing with the funky recoil on shot follow through. No peripheral add on equipment needed for PCP. Open the box, insert the batteries for the electronics and start shooting.

    On second thought, why put this on the gun? Add the springer mechanism to your bicycle pump. Maybe pressurize the compression cylinder to 100 psi with your garage air compressor. Compress the spring on the down stroke of the bicycle pump handle. Give the pump handle a quarter turn to lock it in the down position. Release the spring sear to do its’ work compressing the 100 psi air further. Repeat as necessary? Would that speed the pump process to reach a usable volume and pressure of air?

    Like I said, I know hardly anything. I was just thinking. Happy New Year.


    • If you’re already putting effort in cocking the spring why not just compress the piston that the spring would be pushing? You’d save one step and you’d have a multi-pump pneumatic ;-)

      J-F


    • Ohio Paco,

      Welcome to the blog!

      I don’t know if you have a great idea or not. I need to read it some more, to get my head around what you have said. But thanks for sharing your ideas with us.

      Happy New Year,

      B.B.


      • What the gentleman said is to attach a Benji Disco on top of Diana 48 so he can cock and dry fire the 48 a couple times and that will charge the Disco I think ? Does that sound right?


        • Not sure what the dimensions of the Discovery reservoir are, but considering the tank on my Marauder takes 10 strokes of the pump per 100PSI, and that has something like a 12-18 inch stroke length, think how much it would take from a 6″ spring gun stroke to produce an effective pressure.

          Remember, a spring gun (even a “nitro piston”) starts with the cylinder at ambient air pressure — 15PSI. Ignore the transfer port, pretend the end of the cylinder is blocked off… Say the piston stroke is 6″, and the piston stroke ends with an air gap of 0.06″… That’s a 100:1 compression ratio — the final /peak/ pressure would be 1500PSI — but the first three inches of the stroke only raise the pressure to 30PSI, the next 1.5″ bring it to 60PSI, 0.75″ to 120PSI, 0.375″ to 240PSI, 0.1875 to 480PSI, 0.09375 to 960PSI…

          Add in the transfer port and the increasing volume of the barrel bore as the pellet moves, and the peak pressure may not exceed 900PSI — but is sustained for a few milliseconds.


      • I brought this down here. The compresed air from cocking the spring on a plunger cant be turned into high preasure unless it has multiple stages of preasure to increase the psi. So I would say no. Somebody correct me if Im wrong. I may not understand completly what Paco means.

        “Wulfraed Says:

        January 1, 2014 at 12:28 pm

        You are still talking about using one compressible gas to compress a second compressible gas, and that second gas is already starting at fairly high pressure.

        Ah — that link does suggest why most guns using gas springs make the larger shell the moving mass, rather than the shaft… Since most people cock the gun starting muzzle upward, the sealant oil would rest at the shaft seal, rather than on the internal piston head.

        The 30-40lbs “cocking force” is a misleading measure as that goes through a number of levers; the arc may span 18+ inches for a mere 6 inch piston stroke. I’m not sure of the dimensions of the units used in airguns, but presuming 3/4″ diameter one has a piston surface of .44 in^2, and a strut with an internal pressure of 2000psi compressed is providing 883 pounds on the piston. I don’t know the force advantage of the levers — if the peak advantage comes to 20:1, then this would be about a 40lb cocking force.

        To cock this thing with an air source, you will need to provide enough air to fill the “open” end — for a 6 inch stroke, that means you need enough air to fill a .44×6″ (close to 3 cubic inches) at a pressure slightly higher than the cocked pressure of the unit (to allow for parasitic losses). Say the source reservoir is 12 inches long and the same diameter. When you open the valve you create a joint reservoir 18 inches long, and you need just over 2000PSI in that 18 inch volume… That implies the 12 inch reservoir had to start just over 3000PSI.

        You would get just ONE cocking cycle out of that. After cocking, and the valve closes, the 12″ reservoir is down to just 2000PSI. And you imply you will then bleed out the 2000PSI air from the piston-side of the valve to leave the strut latched with 2000PSI behind it. Open the valve to cock a second time, and the residual pressure is now down to around 1400PSI.

        Reply

        Gunfun1 Says:

        January 1, 2014 at 3:51 pm

        Wulfraed thanks. That is where I was having the problem figuring this out. How much psi would make enough torque to cock the nitro piston.

        And I think I was explaining this part incorrect. The nitro piston is in a chamber in the tube separated from the air pressure chamber that transfers the air to the barrel. Once you push the nitro piston forward against a a stop its locked in place by the compressed air pressure. So now you pull the trigger and the sear releases the plunger so the nitro piston only does its normal job of transferring air to the barrel. The nitro piston doesn’t move. Only the plunger goes forward. And this way you wouldn’t have to worry about how the fps progressively changes on our modern day PCP guns. the nitro piston could be more consistant in a sense.

        The air bleed would be in-between the the compressed air chamber valve to let air bleed out so you could push the spring or nitro piston back to latch the trigger mechanism. You would then close the air bleed and pressurize the air chamber to cock the spring or nitro piston. At that point load the pellet in the barrel and shoot.

        I wonder if a nitro piston could be scaled down so it could be easier to cock and still have enough power on the air transfer side to make maybe 350 or 400 fps and maybe get 3 cocks from the high pressure compressed air chamber side.

        Hopefully I’m explaining this right. And I would really like to know if the scaled down version could be a possibility”


        • I think, Gunfun1, that you are describing a “Rube Ginsberg” way of developing adequate pressure to fire a pellet. Of course low pressure air could be made to produce high pressure air,, but the linkage needed would mean that the gun on which it was mounted would need to be carried by truck.

          What ever force is needed to make the pellet go out of the barrel,, must, in some way, be put into the gun. There aren’t any short cuts.. that’s why faster spring guns are harder to cock than slower ones.

          Consider what is needed to fill a scuba tank. If you look at the compressor, itself,, you will notice something. The cylinders that do the compressing are smaller than on your garage compressor. And the motor is generally larger. Google “shoebox compressor” and you will see a very small compressor,, using a small motor,, but it may take as long as 12 hours to fill your tank,, . Same pressure,, smaller amount of force,,, but much longer fill time.

          It’s all about the physics.
          Ed


          • edlee
            I have a Shoe box compressor. It fills a 4500 psi 80 cubic inch Benjamin carbon fiber tank in about a hour. (not a 80 cubic feet tank they do take much longer) But I can fill about 9 PCP guns before I have to refill it to 4500psi. So to me that is pretty efficient.

            And the shoebox compressors are 3 stage pumps. 1st stage is from a shop compressor at 85psi.
            The second stage takes the pressure to I believe 1500 psi.
            The 3rd stage will then go to 4500 hundred psi if you have it set to shut off at that psi.

            My Shoe box will fill my Marauder in about 5 minutes.


            • I should say the 80 cu in tank in about a hour from 3000 psi to 4500 psi. And the Marauder will fill in about 5 minutes from 2200 psi to 3200 psi.

              Sorry that is mis-leading it sounds like I ment from empty (0 psi). If from 0 psi It would take longer to fill each of the above.


  45. Build it and they shall come? :)

    After reading the blog and nearly every comment, as far as I can tell, this would be marketed to entry level, adult airgun plinkers. Any PCP in the hands of unsupervised little johnnie, is not going to make it past the liability/risk lawyers. Give it some thought with just the filling process and constant threat of what a 1000-1500psi vessel can do.

    So, given it is for entry level adult airgun, what does it need to provide? It has to provide value over any other option at the same price point. As what was mentioned in the comments, and last line in blog, the cost of rifle and pump must be included. So be it $150, $200, etc, need to compare to what is available already. The power plant itself, is not great enough a selling point, on its own.

    Accuracy and power has to be equal or better than multi-pump or co2 offerings in this price range. Ideally, the same or better power and accuracy of a same price break-barrel. We can argue the no recoil angle, but if it is more accurate and more powerful, and less money, what would most first time buyers choose?

    If the specialized low-cost, low pressure pump is developed, it may end up being a barrier vs a stepping stone. One of the reasons that the disco became a good stepping stone was the fact that the support equipment did not need to be upgraded to move on to a marauder or other pcp. The package has to really “wow” them to make the next investment level of pcp. Another pump and gun. I think, at the very minimum, the pump would need to be able to go to 2Kpsi for a disco or challenger. That would also help bring down the cost of entry on that platform.

    Anyway, I do think it is a very cool concept, and look forward to seeing the results. As you mentioned in the comments, the pump is probably the harder nut to crack.



    • Would that be Mike M from Flying Dragon? ;) Yes, you would know. :) I have seen regulated Ninja bottles added to your guns for a mere $200 total.


  46. i think this is an excellent idea . there are several on a limited budget that drool for a pcp. all the bells n whistles don’t help, just cost. im ready to read more on this report. lets hope all works as expected . as for the straw barrel, mods might be in the future for the same people on limited budgets and makes for some very happy campers b.b.


  47. A low pressure PCP gun is something that interests me. I’m talking tire pressure PCP gun. 50 to 60 psi at the most that is used for each shot.
    And I don’t care if its made out of PVC for the proof of concept. I ain’t putting 3000 psi in the gun and it won’t never see above 200 psi in the reservoir. Here is one that has its own pump in this video. I could call it a proof of concept gun. I would like to take the design and Incorporated it into something we are use to seeing. And hang some modern day sniper rifle skin around the outside of the gun and make the internals out of something more durable than PVC. It could be a cool gun.

    And you could make a air reservoir that you wear on your back like a back pack that was connected to the gun. That should give a fair amount of shots.

    And the gun in the video is shooting darts. But the projectile could easily be changed to something else. What if the production gun looked like a .50 cal. BMG Sniper rifle that shot a .50 cal ball of some sort. I could have fun with it.

    http://www.youtube.com/watch?v=L4OHzcXmEjk&feature=player_detailpage


  48. GF1

    If you want me to, I can see if I can blow a pellet through an AF LW barrel with 100 psi of air. .177 or .22 ….take your pick.

    twotalon


    • TT
      Not going to happen with a pellet. Don’t wast your time. But if you find the just right diameter round ball. Kind of like how the Avanti 499 barrel and precision ground round balls work together. I think you will have a little better chance. ;)

      But don’t do it if your worried about messing up your LW barrels. That just made me wince. :)




          • GF1

            We get a couple problems here…
            With bbs, anything will at least push them out the barrel , but pellets take more . If you don’t shove them hard enough, they get stuck, so we have to surpass that pressure . We have to push them hard enough that variation in fit does not cause any extreme velocity variation between shots.
            Then we have to worry about how low can the power be and still sell. We need to get enough range out of it .

            I have no idea where the line would have to be drawn for a minimum operating pressure, but I am sure that it would have to be a lot more than you can get from a tire pump or shop compressor.
            Maybe we need an air pressure gage fudged onto a 397 or 1377 ? We could find a pressure that we must exceed, then fill to something higher and try to get the valve to self regulate.

            I know this is all off the main topic of making a PCP for under a “C” note , but I am sure that support equipment is still going to cost.

            twotalon



              • The more I think about it. I believe the 499 barrel and the Avanti ground steel shot would be the trick to a low preasure shot.

                Or a rifled barrel even with the Avanti ammo. The rifling along with the contact area of the round ball would make very little resistance. A big plus to make low preasure work.

                A pellet is desined to have resitance when it fires. So I would have to say the pellet wouldnt need tested. its out of the equation.
                I got a old Disco barrel I think I will try blowing through with my shop compresor at diferent presure to see what happens.

                I will see how low of preasure will shoot the BB.


              • GF1

                A bb or dart should blow right through with little pressure needed. But again, how much range do you want to get out of it . If you can get the velocity of a Red Ryder (300 fps), it should be adequate for short range plinking (basement or living room, depending on how big your house is ). But do you really want the extra fill and equipment problems of a PCP for this ? Most would rather cock and shoot .

                twotalon



  49. Tin Can Man, Gunfun1 and any others interested,

    I did some calculations today to check the feasibility of an air tube with a spring/bladder controlled piston to keep constant pressure in the tube. These calculations assume the design would feed air from the air storage tube directly to power a projectile (pellets/dart/ball).

    I started by looking at the Benjamin Discovery as a reference gun. It has approximately 8 cubic inches of space in its air tube to hold pressurized air. Given a fill pressure of 2000 psi, we find it holds about 17.4 liters (.61 cubic feet) of gas at room temperature. If we use this as a goal for the amount of air to hold in the new design, we find the following.

    Assuming we use an aluminum tube 2″ in diameter and an inside diameter of 1.75″, we would need a tube over 4 feet long to hold the 17.4 liters of air at 120 psi. Increasing the pressure to 208 psi, we can get the tube length down to a more reasonable 32″.

    Now there are a few problems with the design at this point.
    1) There isn’t any room designed in the tube for the spring/bladder.
    2) This will be fewer shots available than a Discovery because we have to use more volume for each shot to make up for the reduced pressure.
    3) The spring/bladder would be required to apply 1144 lbs of force to the piston to equal the 208 psi pressure of the compressed air! This is calculated with a piston surface area of 5.5″ (Area = pi * D = pi * 1.75).

    This information makes it look like this idea won’t work out (at least not easily).

    I think my calculations are correct, but it would be nice if someone will check them. I used the combined gas law, and the formulas for pressure (p = F/A), cylinder volume and area of a circle. For the combined gas law I used the calculator at
    http://easycalculation.com/chemistry/combined-gas-law.php
    The units also have to be converted since the calculator takes kilopascals for pressure, liters for volume and Kelvin for temperature.

    Thanks,
    Daniel


    • Oops! Big mistake! pi * D is the circumference of a circle, not the area! Area = pi * r^2. The piston has a diameter of 1.75″ so the radius is 0.875 and the area would be 2.41 square inches. Putting that in F = p*A, we get a force of 501 lbs required for the spring/bladder. That is more reasonable.

      Trying the same equation for a spring/bladder using 2000 psi in a Discovery tube (inside diameter=0.746″), we get a spring/bladder force of 874 lbs required.

      So the idea might work, but there are problems to work out.

      Daniel


  50. Here is the 2 different systems I have questions about.

    First one will be easy to find out about tomorrow. Can a steel BB be shot out of a rifled barrel at very low pressure? 100 psi or lower. I’m sure some body tried before but I want to know for myself. So will see how that goes. And even chrony the BB’s if they shoot.

    The second system I believe what some people are talking about. Like what you just talked about 22 multi-shot.

    A gas spring with hydraulics involved. A bladder I guess your saying. I think this is where things got confused from what I was trying to say. I used a bladder to demonstrate a nitrogen piston like what is used in some of the break barrel guns today. Probably wrong example. So I posted a link about a nitro piston if you will after I thought about the bladder example.

    Here is were I may not be explaining correctly what I want to know will work.

    I think I will start this way.
    I have a round tube that the outside diameter of a nitro piston can slide freely in forward and backwards, I put a fitting on one side of the tube to apply high pressure air that is stored in a lets say 90 cubic foot 4500 psi carbon fiber tank.
    Now I make a o-ring groove in the nitro piston body and put a o-ring on the body. The body gets slipped in the tube now with the back side first where the o-ring is at facing towards the high pressure air inlet.

    The tube is a little longer than the stroke of the rod that is in the nitro piston. Now I put a cap on the other side that has a hole in it with a o-ring in it. So now I have 1 tube that has the nitro piston in it with the rod sticking out of it. It is its own enclosed compartment that houses the nitro piston.

    Next I get another tube that is the same length as the stroke of the rod. I put a cap on one side with a hole in it with a o-ring then I slide the rod from our other assembly into that hole. I now put the piston head on the rod and put a cap on the other side of the tube with a hole in it with a o-ring.

    That hole will get a steel rod going through that hole and it will rest up against the piston head. That rod will have a groove in the other end of it to catch and latch the trigger assembly. Also that tube will have a hole in it on the top so it can transfer air to the barrel when the trigger releases the piston.

    So here is how the gun would get cocked.
    No air in the first tube. It would be bled out. And that tube is placed with the high pressure fill toward the muzzle end of the gun. Then you would push the rod in the other tube forward (the rod that latches the trigger and is pushing against piston head). It will push real easy all you would feel is the drag of the o-ring on the nitro piston body sliding on the wall of the tube it is in. That is now a dead stop holding the piston from coming back. So now the piston and stop is holding the nitro piston and body in the other tube against the high pressure fill port.

    I now close the air bleed. Then add high pressure air to the first chamber. It now starts moving the body until it compresses and bottoms out the nitro piston body on the cap that the piston rod is sticking through. The nitro piston body is held tight against that cap. It would hopefully hold air forever till I bled it out. Even after I pull the trigger to release the piston in the other sealed chamber. There would still be air locking the nitro piston rock solid tight in place.

    To re-cock the gun I would bleed the air then repeat the process above. And the pellet would be loaded just like you would with the bolt on a Discovery rifle.

    And if you understand what I just said you will see it is really one main system working two separate ways. One chamber cocks the gun while the other separate chamber is waiting for the piston to release in the normal way a nitro piston would in a break barrel rifle. So the gun would always have a fairly same fps when you shoot.

    So you see there is no air pressure or hydraulic fluid or water trying to fight each other for the same space. All I want to do is use the air to cock and hold the nitro piston in place. The high pressure air is acting like the break barrel linkage and holding it in that locked position. Then after its locked the other air chamber just transfers the lower pressure air through the transfer port to the barrel.

    Now here is my big question. Can that 90 cubic foot 4500 psi carbon fiber tank use its high pressure air to push the nitro piston body and hold it in place till you make a shot? And can that be done more than one time with the 4500 psi 90 cubic foot tank?

    All I want to know is if it can be done. If only once or twice then there would be no reason to think about producing the gun. I’m just talking again proof of concept.

    So Am I right. What I’m talking about is a air assisted cocking device not a bladder. Right


    • So,, If I get this right,, you have a 90 cu ft , 4500 psi tank attached to your new air rifle??? And each time you cock,, or pressurize your nitro spring,, you release the air used to do so. It make me wonder why you need the spring in the middle.
      Ed


      • Why I used that big tank as example was to see if it could be cocked more than once.

        What if that tank could cock the gun lets say 10 times. If you then put a tank in place of the butt stock like a AirForce gun and another one under the gun like a Marauder or something then you could maybe get 5 cocks from the air that was stored in the gun.

        And what spring in the middle. You mean the nitro piston. If that’s what you mean yes it is way more efficient using the air like a normal modern day PCP does. This was just a idea. But if the nitro piston could be cocked this way the nitro piston would produce pretty well the same fps everytime its fired. You wouldn’t have to worry about finding the right fill pressure and setting up your striker and spring to hit the air valve to get the usable shots you want. Again just a thought. Or maybe some body could figure out a valve so you could use one system (PCP) or the nitro piston. You could have a dual power source in one gun. Again just a idea.

        But if read down below we could always design a mechanical lever that the air pushes to cock the nitro piston. That could help to reduce the pressure needed to cock the rifle. Again just ideas.

        Do you have a idea to maybe make the system work better? Maybe more to what we are seeing that could make the system work more effectively? Could be something simple. I don’t know. And maybe the Idea is done and useless.


  51. TT

    You got to remember how this all started. The other day BB brought up the $100 PCP and everybody started posting ideas of what it could be.

    So one of my thoughts was the potatoe guns. Then air powered. So then came the idea of what projectile to use. Well obviously certain ones wouldn’t perform as well.

    But remember nobody said anything about shot count or anything. The thought was could a precharged pneumatic gun be made for under $100. At first and for that fact we don’t know if his $100 gun can shoot or how far or how many times it can from one fill. Like I said I’m sure it can fire and probably multiple times from one fill. But thats BB’s next report and he said it already knows it will. But he wanted to get people thinking about this.

    So that is what got my idea started about what projectile and how to fill the gun with low pressure so a new pump wouldn’t need designed. So everybody could have a precharged gun even if it only shot one time. And all the extra support equipment wouldn’t need to be purchased.

    Maybe it wouldn’t be a efficient design right now but in time maybe more thought could make it work better.

    And that brings me to the nitro piston idea. Maybe the air pressure isn’t going to be the right thing to use to cock the nitro piston. Put if you look at my terrible little drawing I made. If somebody that deals with stuff (air gun design) thinks about what I did it could make a gun that I don’t think exists right now.

    A under lever nitro piston gun. I know off subject now. And I’m sure it cant be made for $100 and its not a PCP gun. But it could be a way to have a solid barrel that doesn’t have to break to cock the nitro piston.

    And back to the idea of using air pressure to cock the nitro piston. If it needed more leverage a linkage could get designed so the air pressure pushed a linkage that mechanically cocked the nitro piston. And maybe then you could get more cockings from one PCP storage tank. See what I mean there is more ways to do stuff when you think about it.

    So when I’m bringing this stuff up I’m not trying to prove that something will work. I’m bringing it up so we can discuss the possibility’s of it working.

    And I cant wait to see BB and Dennis gun work.


    • Ignore which part is moving.
      Ignore what your external air supply source comes from.
      Ignore the thickness of the “gas spring” tube walls.

      For simplicity, assume a 1″ diameter cylinder (since we ignore the spring thickness it is also 1″ diameter)
      Also assume a 6″ stroke for the gas spring.
      Assume that the gas spring internal pressure is 2000PSI WHEN COCKED (full compression) (any residual pressure in the gas spring when in the “fired” state doesn’t really matter)
      Assume 1 Bar = 15PSI, so 2000PSI is 134Bar (rounding up, to account for later losses)

      This means the chamber used to propel the pellet, using ambient air pressure, is
      1/2 ^ 2 * PI * 6 => 1.5*PI cubic inches (4.71 cubic inches). That is ALL the air used to shoot the pellet.

      In order to cock the gas spring requires the chamber to be at 134Bar. That equates to using 631 cubic inches (at atmospheric pressure) of air to cock a 4.71 cubic inch chamber.

      80 cubic inch (at atmospheric) tank at 4500… 300 Bar — less 134 Bar means you have 166 Bar to play with. 166 * 80 / 631 => 21… If I haven’t totally flummoxed this thing, you could get 21 recocks from your tank before the pressure falls below the usable limit.

      I suspect just ONE refill of a PCP gets more than that many shots, and you likely have 5 to 10 refills available on a Discovery.


      • Ok I know all of this is in front of me in black and white. But sometimes I need help with the understanding part of what the formulas mean.

        And so you probably already know at work I make stuff and put it together. But I get info from and work with the engineers at work. So your the engineer right now Wulfraed. And these questions will probably sound dumb to you.

        And here I go in my simple way if you will. I’m not worried so much about the side of the system that shoots the pellet (I don’t think).

        Here is the part that I need to understand right now. I do understand what this means 166 * 80 / 631 => 21

        But you mean the gun could get cocked 21 times with a small 80 cubic (inch) guppy tank at 4500 psi. That tank is about 15″ long x 5″ diameter.

        Or did you mean the big 4500 psi 80 cubic (feet) tank would be able to cock the gun 21 times. That tank is about 30″ long x 8″ diameter.

        If the 80 cubic (inch) tank will do 21 shots then I would consider that good.

        But if you mean the 80 cubic (feet) tank getting 21 shots that’s just to big of a tank to carry around.

        So then I have to ask If the size of the tank is reduced down to 40 cubic (feet) can we get about 10 cocks of the nitro piston?
        Does it work that way if you reduce it down? And how long and what diameter would that tank be? If 40 cubic (feet) would cock the gun the 10 times that would still be respectable shots and a respectable size air tank to mount to the gun. If so that also would be good.


        • You had earlier emphasized you had an 80 cubic INCH tank, so all my computations were done using cubic inches. {I’m still waiting for a third party to jump in and point out blatant mistakes — I’m a software engineer, not physical engineer)

          I’ve also presumed that those capacities are in ambient pressure (or, if you will, if you filled the tank with water, then poured the water into a graduated beaker, the beaker would measure 80cubic inches of water [ignoring that no one makes beakers in cubic inches these days]).

          2.5″ radius ^2 * PI => 19 square inches * 15″ => 294 cubic inches

          How thick are the walls of that tank?! The dimensions you give make the outside nearly 300 cubic inches. Even if we assume only half the exterior volume is available for holding air, that’s coming out to 150 cubic inches are ambient pressure — 80ci implies a partial vacuum.

          Let’s try the 80CF tank

          8″ => .67′; 30″ => 2.5′

          .33 radius ^2 * PI => 0.34 sq.ft * 2.5 => 0.85 cubic feet. This tank must be defining 80CF as how much “ambient” air can be stuffed into it at the rated pressure. Though I’m now coming up with 255 cubic feet if 4500PSI. 170CF at 3000PSI.

          Looking up a common 3000PSI 80CF Aluminum tank, the dimensions (exterior) are 26×7.25 inches, 0.62 cubic foot, and at 200Bar I’m getting 124CF… Wall thickness and the valve end must knock some off of that… I’m getting 18″ long

          Assuming the large tanks are sized by how much non-compressed air they contain 1) a 4500PSI tank would be much smaller than you state, given that 3000PSI 80CF tanks are smaller than your 30×8 [26x7.25 listed]. 2) Assuming a 3000PSI (200Bar) 80CF compressed volume, that is equivalent to 12x12x12 * 80 => 138240 cubic inches worth of total air — but using a lower limit of 2000PSI to fully cock the gas strut means you only have 200-134 => 66Bar of air to play with. Or call it 1/3 of the 80CF is available. 80/3 => 26.6 * 12x12x12 => 46080 cubic inches, and I’d previously computed that you need 631ci to cock the system…

          So the typical aluminum 80cf (uncompressed volume) dive tank might cock your design 73 times. (And a tank whose uncompressed volume was 80ci won’t cock it once, since you need 631ci worth of air)

          NOTE: PyramydAir lists the Marauder as a 215cc tank — I’m pretty certain that is “water displacement” not maximum air equivalent. 215cc comes to 13ci, which fits for a tube 1.2″ diameter and 15″ long [I've not measured the tube, just working numbers that seem reasonable dimensions]. At 200Bar, the Marauder holds 2600ci of air. 1/3 of that covers the 3000->2000PSI or 867ci of air.

          The tank of a Marauder, filled to 3000PSI, would only cock your mechanism ONE TIME…

          The same tank, using direct propulsion, can handle 6 magazines — 60 total shots.

          OH another consideration… My computation for cocking the mechanism assume the air is regulated to just over the cocking max — the 2000PSI. You get even fewer shots if the air is unregulated as you are pressurizing the chamber above the point needed to achieve full cock.

          If you don’t regulate, and start with a 3000PSI source, you will consume 940ci on the first cocking cycle, not the 631ci optimal amount.

          Also take into account that I’ve specified a hypothetical chamber size (6″ stroke, 1″ diameter)

          Let’s see… PA gives 11″x4″ for the carbon fiber tank (ignoring the fittings)… gives 138ci exterior, rated as a 90ci tank… lose some for the rounded ends of the tank, and thickness… the PA carbon fiber tank would seem to be measured in displacement, not air equivalent. So, being a 300Bar (4500) tank, it would hold 27000ci of air. 300-134 => 166bar available * 90ci => 14940. If regulated to 2000PSI output that would give 14940 / 631 => 23 cocking cycles.. Unregulated, much less (for one thing, it will likely blow your chamber). The first cocking cycle will eat 1413ci (a tenth of the available air).

          That carbon fiber tank can refill a Marauder to 3000PSI 10 times and still not have dropped below 3000PSI. That would be 600 shots from the Marauder using the 3000-2000 band (mine in factory trim prefers 2700-2200, for about 35 shots, so (given a few refills before dropping to 2700) about 400 potential good shots using the carbon fiber tank to refill. 400 vs 20 seems a major advantage to NOT use air to cock a gas strut.


    • Gunfun1,

      I’m trying to understand what you are saying, and I think I might have it.
      1) There is a high pressure “cocking” gas source.
      2) There is a spring of some sort (coil spring, gas spring, bladder, whatever) which is pushed on by the high pressure source.
      3) There is a defined volume of air (call it the “action” volume) on the opposite side of the spring from the high pressure source. This volume of air will propel the pellet. The “action” volume is compressed by the spring pushing on a piston (or that basic idea).
      4) There is a latch mechanism which stops the spring’s piston from compressing the “action” volume to the same pressure as the high pressure “cocking” gas.
      5) The trigger releases the “action” volume to propel the pellet.
      So basically it is similar to a spring piston airgun only the air is pre-compressed instead of compressing when the trigger is pulled.

      Is that correct?

      By the way, I think there are some clever ideas posted under this topic. Like you said, it is a matter of figuring out which ones provide some advantage worth pursuing.

      Thanks,
      Daniel


      • I think I’m going to give that a name right now. A trap door guillotine type of system. And I did see that in my mind also. But really I wanted to cock the gun using air pressure. But maybe what your thinking/we are thinking will work also.

        I think this is what we mean. And again I don’t know if its exactly what you mean so tell me if I’m wrong.

        We have one tube that is 1.5″ in diameter x 15 inches long.

        We add high pressure air to the left side of the tube. And it now pushes a sealed rubber bladder that is filled with nitrogen in it. That bladder is 1.5″ in diameter x 9″ long. We push that bladder that is filled with nitrogen up against the trap door. (Can nitrogen be compressed?)

        And what is on the other side of the trap door. But first the trap door is 9 ” down the tube from where the high pressure air comes in. Hmm same length and diameter as the bladder. And what is in the last 6″ of the enclosed tube on the other side of the trap door. Nothing. Nothing but one hole in the top of the tube that transfers air to the barrel.

        What is going to happen now when the trap door gets opened abruptly when we pull the trigger. The high pressure air will make that bladder move to the right and turn it into a piston like on the end of a nitro piston rod.

        That bladder now pushes air out of the hole in the top of the tube that transfers air to the barrel.

        But here is the question how much air pressure is pushed through the hole in the tube and transferred to the barrel to make the pellet move. I think 4.71 cu. inches of air is what was said above that was needed to move the pellet.

        So how much high pressure air is needed on the left side to compress the nitrogen bladder/piston up against the trap door to produce 4.71 cubic inches of transfer air on the right side of the bladder?

        If the bladder moving to the right when the trap door is opened and it can produce enough air to move the pellet.

        How many times could we cock this mechanism with 80 cu. inches of air @ 4500 psi. and like said above regulate the air pressure. Again if the above can be done. And again this is all just a idea. And maybe it wont be as efficient as a Marauder or Disco for shot count verses fill pressure. But first things first. Will it work?

        Is that what you mean also .22 multi-shot?


        • Yes, Nitrogen compresses… Just like hydrogen, helium, oxygen, chlorine, fluorine, neon, xenon, argon, radon, carbon dioxide, and any other substance that is in a gaseous state at room temperature and atmospheric pressure. CO2 liquifies around 800PSI room temperature, sublimates at -109degF at atmospheric pressure (dry ice).

          Which leads back to the futility of using one compressible gas to compress another compressible gas: at pressures below the “inside” pressure of the bladder (when uncompressed), the bladder will act much as a solid plug would (ie; it takes up chamber space, reducing the volume on “outside” air that is required to reach a given pressure). Once the injected air matches the pressure inside the bladder, both the bladder and the injected air are being compressed maintaining pressure equilibrium between the inside and outside.

          The bladder will not save you injection air since, as it compresses, it results in a correspondingly larger injection chamber which, in turn, requires more pressurized air to fill. Replace the bladder with a solid (non compressible) rubber rod, and you net the same effect using less air as the injection chamber is smaller.

          So how much high pressure air is needed on the left side to compress the nitrogen bladder/piston up against the trap door to produce 4.71 cubic inches of transfer air on the right side of the bladder?

          You keep leaving out one factor: the pressure of that 4.71ci. As I recall, that was based upon some hypothetical spring-piston chamber and was the volume of the chamber when the spring was in the cocked position. That defined the volume of air used per shot. But the pressure depended upon the compression ratio during firing (ignore the transfer port to the pellet).

          Let me restart with the hypothetical spring gun: 1″ diameter, 6″ chamber, 5.9″ stroke (so 0.1″ length uncocked, the distance between chamber end and piston top).

          Vu = 0.5^2*PI * 0.1 = 0.0785ci (volume uncocked)
          Vc = 0.5^2*PI * 6.0 = 4.71ci (volume cocked)
          Vs = Vc – Vu = 4.631 (volume stroke) {compression ratio is defined as (Vs + Vu) / Vu — mainly as Vu in engines can’t be easily computed from diameter and length, but since VS+Vu => Vc…}

          CR = Vc / Vu = 60:1 (actual pressure ratio will be higher, since compressing the air produces heat, and hotter air tries to expand more).

          Simplifying to 15PSI as 1bar (rather than 14.7) that gives a pressure of 60*15 => 900PSI — a bit over the pressure of a CO2 gun, maybe giving up 600fps? (Remember, my basis is from a hypothetical piston/cylinder).

          Now — what is the static pressure inside your proposed bladder, when sitting on a table? If the static pressure is greater than 900PSI, you can replace it with a solid chunk of rubber since it won’t become more compressed. If the static pressure is lower than 900PSI, it is going to compress until the pressure becomes more than the 900PSI. How much compression depends on what the starting pressure is, and since the diameter is fixed by the cylinder size, it will become shorter to raise the pressure (something else you have overlooked: as the pressure goes up, so will the friction caused by all that rubber pressing against the side walls of the cylinder… That’s a lot of surface area that needs to be overcome).

          Since you are using one gas to compress another gas, the pressure on the inlet side will also have to be just over 900PSI — and NOTE: this is the /residual/ pressure /after/ the bladder has been shoved to the right to produce the 900PSI “firing” volume.

          Since you haven’t specified the static pressure of your bladder, one can not compute how much compression it will take. If the static pressure is 450PSI, then raising it to 900PSI will result in the length of the bladder shortening by 50%.

          For the moment, let’s replace your bladder with a 9″ solid rubber cylinder, with the ends cupped so that at the end of the stroke there is that 0.0785ci chamber remaining (also, I’m staying with the 1″ diameter, rather than your 1.5″… This still gives your overall 15″ tube, the cocked position is when the cylinder is completely to the inlet side, fired is completely to the outlet side). So… AFTER the rod has moved 6″ to produce the 900PSI on the firing end (the 0.0785ci chamber) you have to have a residual 900PSI on the left side (4.71 + 0.0785ci). The compression ratio is identical at 60:1 but you have a “starting pressure” of 900PSI rather than 15PSI. That means the “cocked” air pressure on the inlet side is 54000PSI! (yes, fifty-four thousand, not fifty-four hundred). I have NO IDEA where you will find a pump that can produce THAT pressure.

          Now, let’s replace that 9″ rubber cylinder with a 1″ rubber cylinder (essentially, a pair of piston seals placed back to back). Keep the 6″ stroke. Let’s assume only the firing end is cupped to result in that 0.0785ci chamber; the other side is flat, giving an 8″ inlet air chamber, and fired position is 14″ inlet side.

          Vc = 0.5^2*PI * 8 => 6.28ci (cocked and uncocked are reversed here)
          Vu = 0.5^2*PI * 14 => 11.0

          CR = Vu / Vc => 1.75

          Pressure Vu of 900PSI means pressure Vc of 900 * 1.75 => 1575PSI cocked.

          Depending on the static pressure of your bladder, the pressure required will vary between those two limits. If the static pressure is atmospheric, then each doubling of pressure will shrink the length by 50%, increasing the inlet chamber size. Let’s assume the static pressure is 900PSI — that means the fired position will have the 0.0785ci chamber at 900PSI (remember, I’m ignoring the transfer port); the bladder will be fully extended (9″) at 900PSI, and the inlet chamber will be 6″ at 900PSI.

          6″ + 9″ (let’s ignore the 0.1″ chamber end) is

          Vu = 0.5^2*PI * (6 + 9) => 11.78ci
          Vc = 0.5^2*PI * 9 => 7.07ci (both the bladder and inlet compress equally)

          CR = Vu / Vc => 1.666

          Pressure Vc = Pressure Vu * 1.666 = 900 * 1.666 => 1499PSI (call it 1500PSI or 100bar)

          At that pressure, the bladder will be 5.4″ long with a 3.6″ inlet air chamber. The amount of air in that inlet chamber is 283ci (2.83ci * 100bar)


  52. I think I got what you mean. The bladder needs to be left out of the equation then.

    If I’m getting this right it will take more inlet pressure to compress the nitrogen in the bladder than if we just had the 1″ piston seals that are back to back.

    So I think this is what you mean will happen with just the piston seals. A regulated inlet pressure would need to be determined to move the pistons to the right when the trigger is pulled to get the right amount of airflow to the projectile. So you would have to stop the piston seal in the right spot in the tube to get your compressed air side of the piston seal enough pressure to make enough volume of air on the other side to move the projectile.

    Is that what you mean by this? And I may of missed something but I think that is what you mean.

    “Pressure Vc = Pressure Vu * 1.666 = 900 * 1.666 => 1499PSI (call it 1500PSI or 100bar)

    At that pressure, the bladder will be 5.4″ long with a 3.6″ inlet air chamber. The amount of air in that inlet chamber is 283ci (2.83ci * 100bar)”

    1500 psi regulated inlet pressure using 9″ of the tube for that compressed air on the left side of the piston seals. Then you have 283 cubic inches of air that gets moved to the the gun barrel to shoot the projectile?

    Here is the question I guess then. Is 1500 psi of compressed air enough to send the projectile down the barrel if we put the 2 piston seals in the tube that I guess is 15″ long by 1″ diameter. Have those piston seals stop at the correct spot in the tube to make the compression side of the tube. Then when the trigger is pulled the piston seals move to the right the rest of the distance to transfer air to move the projectile. Right

    If we keep eliminating parts in the process. Why don’t we just determine how much air pressure would be needed to move the projectile down the barrel.

    Then fill a storage chamber on the gun with air and regulate that pressure down to the amount needed to move the projectile out of the barrel when the trigger is pulled. No bladder ,No piston seals to move. Just a open storage reservoir on the gun. And at that point I think we would be able to regulate that 1500 psi way down to move the projectile.

    Something we talked about before. Avanti 499 barrel and a precision ground bb. How much air pressure does that 499′s cocking mechanism make behind the bb to shoot it 240 fps? That would tell alot right there if that was known.

    Maybe we are making it more complicated then it needs to be. Maybe less is better?
    And man this is going to be a book if we keep going this way.


    • Is that what you mean by this? And I may of missed something but I think that is what you mean.

      “Pressure Vc = Pressure Vu * 1.666 = 900 * 1.666 => 1499PSI (call it 1500PSI or 100bar)

      At that pressure, the bladder will be 5.4″ long with a 3.6″ inlet air chamber. The amount of air in that inlet chamber is 283ci (2.83ci * 100bar)”

      1500 psi regulated inlet pressure using 9″ of the tube for that compressed air on the left side of the piston seals. Then you have 283 cubic inches of air that gets moved to the the gun barrel to shoot the projectile?

      You did miss one factor… Those 283ci of air is what is left on the inlet side, still at 900PSI… The outlet side (what goes down the barrel) is the original 4.71ci @ atmospheric that gets rapidly compressed to 0.0785ci @ 900PSI (FYI: that quantity of air would fill a .22 barrel 10 feet long at atmospheric; with an 18″ barrel, the residual as the pellet leaves the muzzle is around 100PSI)

      If we keep eliminating parts in the process. Why don’t we just determine how much air pressure would be needed to move the projectile down the barrel.

      Up to now we’ve ignored any friction and inertia from the pellet — I have no idea how to compute those. But you need to take into account both the peak pressure and the volume of air being moved. Given our 900PSI firing point, and imagining a flat-bottomed pellet, there is only 34 lbs of actual force pushing the bottom of a .22 pellet, and 3.4lbs when it leaves the barrel

      Then fill a storage chamber on the gun with air and regulate that pressure down to the amount needed to move the projectile out of the barrel when the trigger is pulled. No bladder ,No piston seals to move. Just a open storage reservoir on the gun. And at that point I think we would be able to regulate that 1500 psi way down to move the projectile.

      Something we talked about before. Avanti 499 barrel and a precision ground bb. How much air pressure does that 499′s cocking mechanism make behind the bb to shoot it 240 fps? That would tell alot right there if that was known.

      Now you’ve basically defined a single-stroke pneumatic, with just the trigger-valve holding the air from the pellet.

      Or, what may be closer (ignoring regulation), you’ve created the AirForce Micro-Meter tank. As I understand it, the Micro-Meter tank basically has a small inter-chamber under the “top-hat”. The outlet is blocked by the top-hat valve, the other end of the inter-chamber has a pin-hole to the main reservoir. The pin-hole allows the inter-chamber to fill with tank pressure air. When the striker opens the outlet valve, the high-pressure air in the inter-chamber rushes into the barrel to push the pellet, but the pin-hole is so small that the valve closes before much air from the main tank can flow into the chamber.

      You remove your entire 1×15″ tube, and just put a 0.0785ci pocket. You fill that pocket to 900PSI, and you now have the 4.71ci (atmospheric) amount of air. Heck, your coupling mechanism is likely going to have a larger volume that this.


  53. Now your talking about what Im interested in. The micro meter AirForce tank. I did not realize they worked like that to release air.

    Me and twotalon talked before about the shot string and fps of the pellet with the micro meter tank when I got my Talon SS.

    That is what I would like to see happen with a even lower air presure system.

    I know the micro meter tank reduces the fps down from the standard tank. If that could be reduced down more maybe a 2 stage pump could be used instead of a 3 stage pump. That could reduce the initial cost of a production gun.

    Finaly back to the topic of the 100 dolllar pcp.


    • Now your talking about what Im interested in. The micro meter AirForce tank. I did not realize they worked like that to release air.

      Take into account that that is just my understanding of the Micro-Meter (mine also seems to have a throat reducer in the top-hat, likely to retain higher pressure as the limited air allowed out by the valve has less space in which to expand).

      I know the micro meter tank reduces the fps down from the standard tank. If that could be reduced down more maybe a 2 stage pump could be used instead of a 3 stage pump. That could reduce the initial cost of a production gun.

      But it achieves that speed reduction by reducing the (compressed) volume of air allowed out per shot, but does not reduce the pressure of that air (it is not a regulator — which is why, while one can get LOTS of shots from the Micro-Meter tank, each shot is at a slightly lower speed; each shot results in the tank pressure being reduced a fraction. The regular tank shows a “bathtub” curve because it lets a high enough volume of air out that the back-pressure can close the valve early).


  54. Let me try again.

    “That could reduce the initial cost of a production gun”

    That could reduce the initial cost of a production pcp gun package.


  55. What about starting with the 1077 instead of the 2100? Have never even held one, but it would seem that you would just need to adapt an air reservoir to replace the CO2 cartridge.


  56. Fwiw, while its not a made in usa crossman product, the xs-60c is being converted to a 1500 psi pcp by a shop here in the us and shipped out the door for $100. Ive got one and am happy with it, although it is pretty loud. I would say B.B. has pretty much been proven correct.


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