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Accessories Building the 0 precharged pneumatic air rifle: Part 3

Building the $100 precharged pneumatic air rifle: Part 3

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

Part 1
Part 2

$100 PCP
The PCP built on a Crosman 2100B chassis.

Today, we’ll start looking at the accuracy of the $100 PCP. This is the test that has concerned me most since we began this experiment. I knew that a Crosman barrel could be very accurate because of the success of the Benjamin Discovery. But the $100 PCP is a job we threw together quickly just to test the concept. And when I say “we,” I mean Dennis Quackenbush, of course. It isn’t fully developed. Will it shoot well or fail miserably? Today, we’ll find out.

Loose barrel
Since this is a lash-up job, there’s nothing connecting the barrel to the reservoir. This is a real free-floated barrel, but that’s not a good thing in this case.

I discussed this with Dennis, who advised me to attach the barrel to the reservoir tube with JB Weld. I was concerned that if I didn’t get the barrel fairly straight, problems would crop up when I scope the rifle. The open sights are mounted to the top of the barrel, so they’ll stay aligned at all times; but the scope base is on top of the receiver. The barrel is separate from that, and that could present a problem.

Crosman 2100B barrel pushed left
The barrel isn’t attached to anything and flexes to the left …

Crosman 2100B barrel pushed right
… and to the right. This had to be addressed before testing.

Thankfully, I’m a highly skilled craftsman, as long-time readers of this blog know all too well. My solution was to install a precision shim between the barrel and reservoir to maintain separation, and then to attach the 2 parts with several strips of linear adhesive material.

In other words, I put a piece of cardboard between the barrel and reservoir tube and then wrapped both with Gorilla tape.

Crosman 2100B shim
A precision shim of technical cardboard was slipped between the barrel and reservoir tube.

Crosman 2100B taped
Then the barrel was taped to the reservoir with Gorilla tape.

Naturally, I don’t expect the blog readers to be capable of skilled work like this. I’m just showing it to you so your repair center will have the information when they do a similar job for you!

Test time
Now, it was time to test the rifle. I shot only pellets, of course, and I decided to start at 10 meters with the open sights that came on the rifle. If I was testing a Crosman 2100B, that’s how I’d start.

First fill
Right away, I messed up and over-filled the gun on the very first fill. I’m not used to the needle on the gauge stopping at the 2,000 psi mark, so I went over and filled to about 2,300 psi. Thankfully, Dennis over-built this rifle, but I didn’t want to test that aspect! Nevertheless, the rifle was filled without incident, so I fired the first 10 shots.

Premier lites
Crosman Premier lites were the first pellets I shot because this is a Crosman rifle, after all. I’ve found that pellets and airguns made by the same manufacturer often do well together.

The first pellet landed to the right of the bull and about right for elevation. I left it alone and fired shot No. 2. Since the pellets were in the white, I could see them without a spotting scope (this was only 10 meters); and they were landing close to each other. I settled in and completed the first 5 shots.

I was so concerned that the pellets might walk as the pressure dropped in the reservoir that I photographed the first group after just 5 shots. Then, I photographed it again after all 10 shots were fired.

Crosman 2100B Premier lite first group after 5
The first 5 shots looked promising. I hoped the group wouldn’t open up too much when all 10 shots had been fired.

After photographing the first 5 shots I returned to the bench and shot the other 5. When I went downrange to change the target I was surprised to see that the final 5 shots hadn’t enlarged the group at all! This is not a common occurrence, and it made me think that I should re-shoot the Premiers with a correct 2,000 psi fill, just to be sure. But I decided to wait until the end of the test to do it.

The first 10-shot group of Premiers measures 0.726 inches between centers. As noted, that size was reached in the first 5 shots.

Crosman 2100B Premier lite first complete group
Ten Crosman Premier lites went into 0.726 inches at 10 meters. Not bad for a start!

RWS Hobbys
After the first group, I adjusted the rear sight to the left, to get the pellets striking inside the bull. Then, I fired the second group with RWS Hobby pellets. After confirming the first pellet did hit in the black, I didn’t look at the target again until going downrange to change it. What I saw was both thrilling and astounding. With open sights, the $100 PCP had put 10 Hobbys into a group that measures 0.534 inches between centers. This isn’t just a good group — it’s a great group when you consider that open sporting sights were used. Granted, I’m only shooting 10 meters here and the group will be larger when the distance increases to 25 yards, but will it be that much larger? I’ll be using a scope, after all. And maybe I haven’t even found the best pellet yet.

Crosman 2100B Hobby group
Ten RWS Hobbys went into 0.534 inches at 10 meters. This is amazing!

After this group, I adjusted the rear sight up one step. Since the next pellet is a heavy one, that would probably keep it is the same place.

H&N Baracuda Match
Although this rifle is producing only 12 foot-pounds of energy, I thought the H&N Baracuda Match pellets might work well. So, I gave them a shot. Ten went into a 0.855-inch group. That’s not terrible; but in light of the others, it’s not as good, either.

Crosman 2100B HN Baracuda Match group
Ten H&N Baracuda Match pellets made a 0.855-inch group.

Air Arms Falcon pellets
Next up were the Falcon pellets from Air Arms. Ten of them went into 0.683 inches. Since this is a domed pellet, it may group better at long range than the Hobby.

Crosman 2100B Falcon group
Ten Air Arms Falcon domes made a 0.683-inch group.

Premier lites
I then shot a final group of Crosman Premier lites — this time with the rifle filled to just 2,000 psi. Ten pellets went into 0.615 inches, making the second-best group of the day, with Hobbys being the best.

Crosman 2100B Premier lite group 2
Ten Crosman Premier lites went into 0.615 inches at 10 meters.

Overall performance
The rifle’s pressure dropped about 800 psi for the 10 shots in each group. So the valve is far from optimum at this point. And the reservoir could stand to be a lot larger.

The trigger is the 2100B trigger. While it does have a long pull, I didn’t find that it caused me any problems. I think it should stay as it is.

The rifle cracks much louder than a Benjamin 392 on 8 pumps. Crosman could shroud the barrel, but I’m going to recommend they don’t. I want to keep the price of the gun down below $100. Let the people who buy them figure out how to quiet their guns. They’re going to anyway.

The verdict?
I’m going to address these next comments to Ed Schultz at Crosman. The $100 PCP tests out the way we both thought it would. You can see the shortcuts I took to stabilize the barrel for today’s test. I would want more than 10 good shots from a rifle like this. I would want at least 20 good, accurate shots of 7.9-grain Premiers going at 850 f.p.s., give or take.

I’m going to continue to test the rifle at greater distances, so there are more reports to come. But there’s no longer any doubt that this is a viable airgun.

89 thoughts on “Building the $100 precharged pneumatic air rifle: Part 3”

  1. So that was the one more thing you needed to do to the gun before you did any accuracy testing.

    If you look at some of the Crosman guns they use a plastic cupped filler that slips between the barrel and the air tube. If I remember right some of the 1377’s have that filler.

    And at the muzzle end the barrel band combination hinge-point on the pump guns pull the barrel and air tube together and hold the barrel secure. So really all your missing right now is that you need to put another band clamp at the muzzle end of the barrel just like the one that is already on the gun. Have the one where it is at now in the top picture then at one by the muzzle. That’s basically how my Discovery’s are set up. Definitely helped to keep the barrel straight on my Discovery’s also.

    And it seems to me this gun could end up being a heck of a good shooter. I’m liking it even more now.

  2. Warning! The following is off subject!

    I have been seriously considering the See All since you introduced it to us. In yesterday’s comments the subject of parallax was brought up and it started to get some of the gears grinding. I remember my experience with a dot on a pistol and how difficult it was to insure proper alignment using only one sight point. I suspect to get true accuracy with this sight will require a repeatable hold/cheek weld/etc.

    While I’m off subject, my reasoning for testing the C96 with the Avantis is that they are slightly larger than the others and likely fit the barrel better, allowing for less gas to escape around them, increasing velocity, and reducing the bouncing around, hopefully increasing accuracy.

      • BB
        Why wouldn’t you want to try the supposedly best ammo if you want to say a bb gun is accurate. If I want accurate then I would try what they say is best.

        You have to try that one more test. If that ammo wasn’t tryed wouldn’t you just wonder in the back of your mind if it was the magic bb. And you would never know if you didn’t try.

        And as far as steel bb’s go there isn’t a big choice anyway so why not have them on hand to try. Heck they usually are cheaper than pellets also.

        • Sorry BB I keep forgetting about time.

          I had one of those crazy stupid day’s today. It was one thing after another and I didn’t even get to eat lunch.

          You wanna know what I did when I finally got everything squared away. I turned on some music and sat down and made some changes on a gun and shot it in the garage for a while.

          Yes I feel much better now.

        • GF1,

          I could write a whole blog about the answer to your question of why I wouldn’t use the most accurate ammo in a test like this. The short answer is this — it may not make a difference. In fact, I’m betting that it won’t.

          Avanti precision ground shot does make a small difference in a 499 target gun, but none at all in a Red Ryder. It’s like using high-test (high octane rating) gasoline in a lawnmower. It doesn’t make the lawnmower cut the grass any better or faster. It simply has no affect, since the difference in quality goes unnoticed because of the slop in the lawnmower technology.

          The C96 pistols sounds like an extremely accurate BB gun, and, when compared to others that are like it, it is. But when you look at the actual level of sophistication, it isn’t in the top group. Only the 499 is in that position.

          So I don’t think the Avanti BBs are going to make any difference as far as accuracy goes. But I will test them because we all want to know for sure. Maybe after the test I will write that other report, if it turns out the way I think it’s going to.


          • BB
            You just brought up a interesting point.

            Maybe the 100 dollar pcp could be a muzzle loader that shoots lead balls. It would then lower the cost possibly by it not having a bolt like the 499. Or I guess maybe even pellets also.

          • For that lawnmower with premium…

            Premium may even run worse… Higher octane fuels are harder to ignite, and the typical magneto powered spark on a mower might be borderline for igniting the fuel.

      • And ok BB you got to do the another barrel band clamp on the gun before you shoot out to the 25 yard mark. I read the blog about the Double Disco earlier and that’s the way my Discovery barrel band clamps are positioned. I guarantee it will help the 100 dollar pcp.

  3. I’d be really interested in the $100 PCP as an entry into PCPs. Buying both pump & gun at once is a bit steep for me at current prices. Ideally, the pump for current Marauders, etc. would fit any $100 PCP Crosman makes & markets. That would let me buy one pump, shoot the $100 PCP until I could buy an upper scale PCP (right now I’m thinking the P-Rod), then continue using the same pump for both guns. Once I get the P-Rod (or M-Rod, or Disco), I’d be able to take a friend shooting, loaning them the $!00 PCP, & intro new folks to shooting.

    • Jim,

      Yes, the current pump will work fine, plus it will be very easy to pump if you stop at 2,000 psi.

      I talked with Ed Schultz of Crosman and he believes as I do that a new less expensive pump is also needed. But as you point out, if you buy what’s there right now, it will work on almost anything.


  4. BB,

    You might still stick a small blob of pig putty, jb weld, or even some thick 2 part epoxy in the crevice between the barrel and cylinder and let the tape hold it in place while it sets up. I think the tape will still have enough flex in it that it could let the barrel shift its poi if bumped while pumping. That shift could make for some aggravating shooting when you move back to 25 yds.


  5. You know, reading the R&D on this aspect of the development process reminds me that I seem to recall the Comedy Channel is looking for a new writer…;) But I also recall (I believe) the Futurist Master Engineer Heinlein saying words to the effect, “The fix may be stupid…but if it works, it ain’t stupid.” Maybe it was Bucky Fuller, but the point remains the same.
    Go B. B.

  6. You do realize that should someone introduce this PCP to the market, another cottage industry will be created to meet the needs of the owners who wish to upgrade their rifles as has happened to the Discovery, Marauder, AF, etc.?

  7. Dear Mr Pelletier:

    I have been following this blog with the expectation to see something new. As i understand it so far, we are trying to build a discovery for 100$ and to be honest, i think that is an unfair comparison. If you do speak with Mr Shultz, why not approach this as a 2100 that does not need to be pumped, instead than a disco that has to be shortchanged? i think expecting mid 8s with this gun and 20 shots is possibly doable, but i am happy with my 2100 shooting mid to high 6s… and if i did not have to pump it all the time, it would be great!. so why not aim for a 700 fps shooter that will certainly be able to provide more shots than the 850 you are trying to reach? Most of us agree that that power level is appropriate. many rifles shoot well at that power and are used for occasional pesting as well as short to mid range shooting (type of shooting most air gunners realistically do). But lets not call it 700 and do 550… 700 real fps with premiers lites will do the job (a bit faster than a R7?). plus i am sure that the inners of the 2100 shroud may accomodate a couple of baffles if we shortened the straw barrel a couple of inches…
    thank you for your time, and i will be watching this space anxiously…

  8. At a 100$ shooting like that, I’d get one and get the repeater breech that uses M-Rod mags to put on it, try to tune it for more shots per fill and shoot away with my 200$ plastic M-rod.

    I think it would be perfect for the Crosman custom shop. You start with a basic PCP, single shot and plastic stock for 100$ and you add what you want to it.


    • J-F

      “I think it would be perfect for the Crosman custom shop. You start with a basic PCP, single shot and plastic stock for 100$ and you add what you want to it”

      Dead on. Absolutely the best idea I have heard yet. Then I could even have the option to add a shroud if I want. Or a wood stock. There ain’t enough room here for me to write all the things that could be done or added to the gun. But also have the parts available separately so you can add at your convenience. Or have them build it to what ever degree of mods you want.

  9. That’s quite an achievement to get a pcp of this price to shoot that way. As to B.B.’s engineering skills, a documentary I saw on the Apollo 13 near-disaster (“Houston, we have a problem.”) said that the measure of engineering skill is not based on the materials you have but how ingenious you are with them. In fact, the challenge is all the greater the less you have to work with. They were calling out these geniuses from MIT in the middle of the night to essentially rebuild or rewire the spacecraft at a distance from odds and ends lying around the cockpit. So, there’s no reasons to scorn the cardboard bedding job.

    The accuracy of this rifle raises a longstanding question about pcps which is why this powerplant is so much more accurate than others. The answer that I remember is that it was not really the powerplant at all but the high level of manufacturing that went into these guns. Well, now with this economical model, we have stripped away the expensive manufacturing and have left…surprisingly good accuracy even with the cardboard modification. So maybe there is something intrinsic to this powerplant after all.

    Regarding the cost, it is surely a great achievement to bring a pcp down to this price level. The Discovery was described as a Jurassic Park type innovation in airguns for bringing the price of pcps down to a remotely affordable level, and this gun is way cheaper. But even this new model still bumps up again the mountainous additional costs of the pump or the scuba tank. While the pump is less expensive, you’ll be grinding away every 10 or 20 shots. Seems a little distracting. I just get more enamored all the time with my IZH 61 which I can pick up and fire a hundred shots with in a half hour or so, then put away for next time.

    B.B., regarding your counterexample yesterday of red dots and focal length, I was going to say that the very fact that the focal length was zero as opposed to some small distance puts it in some other category. 🙁 I will have to defer on this one. Wulfraed, I’m sure you’ve got the right answer with your detailed explanation, but I need to look up “collimated” and start from there.

    gunfun1, I’ve been hoping that my years of airgun shooting will translate into archery even though I can hardly practice it. The specific goal is to defeat my brother who is apparently very good with darts although he doesn’t practice much. I don’t know. The one time we shot, I did better overall, but he defeated me in the one round for record. But I think that may have been a fluke.


    • Matt61
      You sound like me and my brother with our friendly little pistol competition. The funny thing is I will accept the challenge with a pistol match. And he usually wins.

      But he wont even think about accepting a challenge from me if it includes rifles. Because I will whomp him in a rifle match. I don’t think he wants to admit I can out shoot him with a rifle. But man he is good with a pistol.

      All in all fun stuff.

    • Mine never did. It’s a horrible long, stiff pull. I rarely, if ever, shoot my nighthawk. It’s especially bad when I try it after the p1 it sits next to. I’ve put several hundred rounds through it, and it still hurts my finger after a couple clips, usually wasting co2.

      • It was the wifes idea (for her). Seems to shoot pretty good, other than the trigger.
        My Rekords are really going to feel light if I shoot this thing very much.


        • TT
          You just made a good point. Maybe a person should keep a gun around that has a little harder trigger than what they are use to. Probably a good way to learn trigger control.

          Then when you go back to your good trigger it will seem easier to use.

  10. Looking at the results this looks like it would be a worthy project for Crosman to pursue I believe that it would be an exceptional gun for $100. One thing I’d like to see is something like the M4-177 made into a pcp. I know that they’d have to rework the power plant since it’s just a pumper but I think it could be done and done fairly inexpensively. I like the tactical look a bit more so I’d be more inclined to buy a tactical looking rifle than a traditional looking one. But that is my personal opinion.

    • I could not agree with you more.
      The M4-177 and the MK-177 would make awesome mid power PCP’s.

      At a 100$ I don’t think people will be expecting a power house, plus with a 1000 fps pellet you won’t be getting a lot of shots. I like PCP’s because you can just fire them for a while without having anything other to do than loading your pellet(s) and sending them downrange and I don’t think I’m alone.
      No cocking, no pumping, nothing. You only have to concentrate on your shot and since it won’t be a hunting rifle why not go for the shot count? Or make two versions! One low velocity/high shot count .177 rifle and one high power/low shot count in .22 for the hunters!


      • I think this is an idea who’s time has come. I don’t really care about power if I had a pcp M4-177 since I’d use it as my indoor target gun so I want lots of shots between fills. But I want that military look so when I pull out my AR15 to go have some fun I have had a full winter of proficiency training with a cheap pcp M4-177. I can always pit a .22lr conversion kit in my AR15 for small game hunting easy enough for the price of a cheap Gamo break barrel. So my main want is a cheap pcp military styled rifle with a high shot count. I like the m-4-177 due to the fact I can use bb’s or 5 shot pellet clips but I really don’t like pumping the gun for each shot that much. Which is why I like pcp so much better.

        • I think the military look or at least a tactical look is the best way to go plastic. Woodgrain plastic is too ugly and those hollow stock look, feel and even sound bad.


          • Military look, tactical look, whatever you want to call it It definitely would give it a bit more credible look since the AR platform does have quite a bit of plastic on it anyway. I argee that the plastic wood is a bit cheesy looking so just taking this concept which is very good to a different model would be very good and would free up that lower rail on the M4-144 for mounting a laser or other goody. This is an idea that has all manner of possibilities.

  11. BB, One of the things I’m so excited about with this gun is that with this capability it’s still so lightweight and I’ve always felt that pcps,at least,could be made a lot lighter.Most airguns seem too heavy,especially with a 1 to 2 lb. scope on them.
    So after you get done waving the aroma of this fresh baked cookie around us you’re going to have to remind us that we can’t have one right? I’m ready to buy one now and I’m wondering if I could get mine at a rake-off price as I prefer electrician’s linear adhesive material in black and would like to install it myself;sort of like a kit version you know.-Tin Can Man-

    • Tin Can Man
      I was going to post a reply and got side tracked. Some guns are good when they are balanced in different ways. Some guns are good when they are heavy.

      But when I shoot a pcp gun that usually doesn’t have a recoil. Or if it does its very mild. I want that gun to be a little different than other guns I shoot.

      Yes light weight. I myself would rather a pcp gun to be light. First you don’t get as fatigued with a lighter gun especially if you are shooting without a rest. Also its better if I’m on a long hike in the woods or hunting to have a lighter rifle. It is even a benefit when you plink. Then another reason for a light gun would be to help a younger person or a person that doesn’t have the physical stamina to hold the gun for a long enough time period to make a comfortable shot.

      So yes definitely make it light.

    • TCM,

      Regarding the black electrician’s linear adhesive material, I’m not sure that changing the spec is safe or even advisable in this situation. Untold hours of research have gone into developing the proper applications of materials and methods for this fix and changing them, even slightly, could upset the applecart.

      I’m not saying it would — just that it could. When the engineering is as razor-edged as it is in this project is, I prefer to be on the safe side.


  12. Great ingenuity. PCP accuracy is an interesting concept although I admit that I’ve never shot one. My pump ups (old Sheridan Blue Streak) require that I take the gun off target, pump, load and settle back in. Same with my Anschutz break barrel, I’m interrupting the bench experience. Not so with any of my semi-auto weapons, I just stay in place, my breathing and trigger pull rhythm is hardly interrupted. Do you think that because you are not disturbing the gun or your environs in between shots coupled with a larger, more consistent propellant than CO2 that you may be able to shoot PCP more accurately?

    • Thinking about this more, my Marlin .22 bolt is my most accurate rifle. I have to work the bolt but the rifle stays mostly planted, I’m not picking it up and changing my position.

    • Eric,

      Since this rifle is also a single-shot and not a repeater, it has to come off the bench for loading, as well. So it isn’t as unmoving as it might sound.

      The 2100B loads from the right side and the process is a bit fiddly. You have to take great care to ensure that the pellet doesn’t flip around in the pellet trough and try to load backwards. This is especially true for the domed pellets.


  13. BB I don’t know how to bring this up. So I will just say it as it is.

    But a little mishap just happened (I call it a wonderful mistake) when you were testing the velocity on the Double Disco. You accidentally tested the velocity with .177 caliber pellets in the Double Disco’s .22 barrel and it shot in the mid 700 fps range and all the way down at 1000 psi. is what the pellet went. And we asked if you would test the accuracy just for the heck of it. Which at this time you haven’t.

    But that brings me to this point. The base gun you started with here has a barrel that will fire a combination of pellets or bb’s. So now I have to request that you also do a test with bb’s on the velocity that they get. And also please test the accuracy of some choice bb’s that are available. this may be a ground breaker also but I don’t think that there are any pcp’s out there available that shoot bb’s or pellets right now.

    I think that the 100 dollar pcp deserves the chance to be called a dual ammo gun also. And for that fact where did the old .177 caliber darts of the 70’s disappear to. BB do you got some of those darts still? Try a couple shots for the heck of it. That was a long time ago that I shot some darts but I remember them to be accurate.

    • GF1,

      I’m going to be serious now. The reason I won’t shoot steel BBs from this gun is the velocity it reaches with them. I have been hit in the face (safety glasses on, thankfully) by a BB fired from a Anics pistol at just 500 f.p.s. It went downrange 10 meters, hit the hard backstop and returned to the firing line to break my lip and draw blood!

      Now, if a BB going just 500 f.p.s can do all that, imagine what one that starts out at 900 f.p-.s. can do!

      It is just too dangerous to try.

      But I know what you want to know. You want to know how accurate a round ball can be when fired from a gun. Well, there were shooters in Ohio in the mid-1800s who wanted to know the same thing, and they had matches with smoothbore guns shooting round balls. They believed that the closer they got the ball to the bore diameter, the more accurate the gun would be. Some of the reports I have read said they could get groups of under 2 inches at 50 yards, which I think it stunning.

      I was going to try this myself, but life is just too short to do everything, and I am still trying to do the other things that interest me. Maybe this is something that you might like to try? If you do, just do it with lead balls and not with steel BBs.


      • BB
        Here is where I was going with the wrong caliber pellet in the wrong caliber barrel thing.

        I was thinking about how there is different head sizes available for particular caliber pellets and people try to find the right fit for accuracy.

        What I was thinking is reverse the idea. I was thinking to take lets say .177 caliber pellet and find a looser fitting pellet head size in .177 caliber so the drag/friction could be reduced and that way a less amount of air would be needed to move the pellet.

        And yes I have tryed some of the available lead balls in some of the guns I have. And it seems to me that getting the power right and the fit of the ball to the barrel makes a difference in accuracy.

        And yes BB No hard backstops for bb’s please.

  14. I like your report on the progress. I had a big laugh at using gorilla tape, the strongest tape on earth ,and your precision shim. have you been watching the red green show? I like that show with all the many uses for the handy man’s secret weapon duck tape. I guess its a free floated barrel. but seriously you have to start somewhere and your keeping my interest up on the $100 pcp

  15. Very nice I just hope that Crosman listens. Though I would through out to Crosman that the Crosman 66 platform may be a better starting point because the pump stroke does not matter any more, and the accuracy is very good with the 66.

    Also if you decide to do a 4th part could I recommend adding a simple homemade piston type pressure regulator between the air tank and the Crosman valve? This would only add about $4 to $5 in materials and about 30 minutes to 1 hour additional build time with the aid of a cheep bench top lathe. Not to mention that if regulated for 1200psi to the valve would give a good MV as well as extremely good results as far as shot to shot consistency both in MV and shot accuracy. Of course it would mean that once the tank pressure got down to about 1250PSI you would not have any more shots until you refill.

    For reference 1200 PSI is about what a stock Crosman 66 gets to on 23 to 26 pumps (once tuned to dump the pressure).

    • DavidS,

      Yes, I will be back with this rifle again.

      And Crosman is considering it.

      I have a pressure regulator like you describe, but I don’t want Crosman to regulate the gun, so I’m not going to. Remember, I’m just doing a proof of concept here — not trying to develop the rifle That work belongs to Crosman.


  16. I also add that a Multi Stroke Pneumatic is the perfect starting point since it is the same technology as a PCP, the MSP just dumps its entire tank each shot, while a PCP gives you more per tank fill.

    • Please allow me to disagree, it may be the best starting point from an accuracy point but if I had a multi-pump as a first airgun I’m not sure I’d still be involved in the sport. They’re a pain to pump especially when you’re a kid, and pumping for max power (which is what you’re looking for when you’re a kid) is very hard.
      I started with a springer and I think it’s the best plateform, you get instant gratification even if you have to work a little harder to get all the accuracy out of the gun.


      • Sorry for the misunderstanding, I meant that if you want to convert an air gun to PCP that has a different powerplant to begin with the MSP (Multi Stroke Pneumatic) is the best thing to convert. As said above this is because the MSP is essentially a PCP that you charge for each shot using a built in pump and dump the entire tank each time. This is true both in theory and in the internal operation of the two guns, they are nearly identical, and hence the many many MSP to PCP conversions that hobby modders have done over the recent years.

        Though to your statement: I probably would have lost interest in AirGuns if I had started with a Springer, because as a kid it was the ability to hit a target at significant range with my MSPs that captured my attention, though that was 24 years ago.

        Now I am one of the Hobby modders with a strong interest in AirGun hunting as well as long range target shooting with guns that every one says can not do it (hence me being a modder, and loving Crosman guns [Easy to soup up for better power and accuracy]).

  17. If Crosman is reading this, if you tune the ratio of spring strength in the valve assembly versus hammer spring so that the gun shoots at about 600fps at 1600PSI with minimal hammer bounce you could probably get a fairly long shot string that is very consistent on power. And this is something that would be easy to do.

    Just figure out what the ideal combo is (by trial and error), and then include a simple power adjuster like that commonly added to the 2240 and similar guns. For that I would recommend building the gun around a 13xx platform base. Start with a 2289, slap on a 14 inch barrel, remove the pump linkage and piston, drill and thread the front portion of the intake port on the valve assembly and screw in a fitting for the tank, make the tank so that the first 7 inches or so fit inside the existing tube, with the front end 2 inches machined externally larger to match the diameter of the tube, and fill the linkage slot. Of course design the tank so that Machine screws inserted in through the Pump Pivot holes in the Pump tube are used to help securely hold the Air tank. This way it would be a modular gun that the user could easily convert between MSP and PCP, and Crosman could sale the Hammer Spring, Modified Valve assembly, Modified barrel band, and Air tank as a conversion kit for the 13xx guns that have at least a 12 inch barrel.

    Then the cost of development is almost non existent, and they have a low end PCP that is affordable and that is built around there very strong and proven platform, with out any of the complaints of to much plastic 🙂 (the few plastic parts on these guns are very sturdy), especially if they include the steel breech by default.

    • Figures, I just created a summer project for my self to make a proof of concept by following my own instructions as just posted :-).

      Now I just need a source of high pressure air that I can afford, is there a PCP hand pump for under $100???

        • Also as for a new one, I have thought about using the design of the pump linkage to make a pump that can achieve 2000 PSI. I know that that is possible because with the pump head space reduced as far as possible the pressure in a 13xx valve assembly has been measured at up to 2600PSI (by the fitting of a pressure gauge to the valve). Beings how inexpensively that design can be implemented you may wish to mention it to Dennis Quackenbiush as a possible design for a PCP hand pump that could be retailed for around $50.00. Of course I would recommend using the pump stroke of the Crosman 66 with the matching linkage as that would give more swept volume per stroke, with out any additional pumping force.

    • I forgot to mention price logic above:

      + 2289g currently retails for $75 ($74.95),
      + The valve mod is almost negligable time less than $0.10 of work once in manufacture.
      + The air tank can be made from a 7 inch piece of high tensile strength solid steel rod costing ~$7.00 retail.
      + And about $5.00 labor (when mas produced).
      + The adapter would cost about $0.50 for both material and labor.
      + The tank to valve fitting and valve could be a high pressure fitting that retails for $1.50
      + The fill nipple retails for $0.75.
      + The barrel band would retail for $1.20 (based on Crosmans current price).

      Then subtract the cost of the Pump linkage, Pump grip, Piston, Pump Cup, and Pump pivot pin, that is about $20 according to the most recent Crosman prices I have.

      Add $ 20 for retail mark up and it is about $90.00

  18. Dear Mr. Pelletier,

    I´m read with high interest this article, is possible to modify a Crosman M4 177 with the same kit?
    In this case there is possibility to buy this custom kit?

    • Pietro,

      Welcome to the blog.

      This gun was not built from a kit. It was made by a man who builds airguns. While it is possible to do0 this to the M4-177, it would have to be done by someone with gunsmithing skills.

      Thank you for your interest.


      • Mr. Pelletier,

        Thank you for your answer, anyway I’m coming with an interesting challenge:
        How modify a CO2 pistol in an PCP pistol:
        Is possible to build an air tank with the same size of a 12gr cartridge and an adapter for the co2 valve in order to fit some co2 pistol?


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