Design an airgun

by Tom Gaylord
Writing as B.B. Pelletier

This report covers:

  • Air gun?
  • What about pneumatics?
  • Can you build a spring-piston gun?
  • Keep it honest
  • Contest?

This report will be different than usual. Today I’m challenging you to design an airgun that we readers can build!

I’m guessing it will be a BB gun, but it doesn’t have to be. I’m guessing it will be a smoothbore, but again, it doesn’t have to be.

Air gun?

When I say build an airgun, it doesn’t have to work with compressed air. The Daisy 179 pistol is considered an airgun, but in reality it is a catapult gun.

Daisy 179
Daisy’s 179 is really a catapult gun.

The Hodges gun of the early 1800s is also a catapult gun, and a powerful one at that. It is said to have been capable of killing medium-sized game such as feral hogs.

Hodges gun
The Hodges catapult gun launched large .40+ caliber lead balls.

And there are slingshot “rifles” being sold on eBay right now. Unfortunately they are made in China, so they won’t see many sales in the US. But that doesn’t mean you can’t build one yourself. There are videos on You Tube about just that.

What about pneumatics?

 Can you build one of them? In the 1990s, when he was learning about airguns, Gary Barnes experimented with low-pressure pneumatics. He discovered that pressures as low as 30 psi were enough to drive large projectiles pretty fast — certainly over 100 f.p.s. Those kind of pressures are easily generated with bicycle pumps and they will push a heavy projectile pretty fast. They weren’t controlled by conventional triggers, but that was just a detail to be worked out.

He even built a multi-pump that ran on lower pressure — certainly no more than 50-60 psi. It reminded me of a slide trombone, and the lesson was — it isn’t air pressure that pushes projectiles, so much as air volume! The pressure was low but the volume was high, so the push was long and gentle.

Can you build a spring-piston gun?

Reader Duskwight from Moscow designed and built his Duskcomb (SP?) rifle — his version of a Whiscomb, where two pistons come together to compress the air. You get a powerful springer with zero recoil. From his reports we know that he invested thousands of dollars in his project — probably more than enough to buy a genuine Whiscomb. But he really wanted to do it and to his credit he saw it through to the end. What was better, he reported the results to us on this blog. As I recall, his rifle weighed more than he wanted, but I believe that it worked.

I don’t expect anyone to go that far, but a simpler spring-piston airgun could be made.

How about starting with a wooden popper toy? They build pressure as the parts are brought together, and I’m sure many of you have played with them.

popper toy
Come on — I know many of you have played with one of these.

The Quackenbush Lightning is a spring-piston airgun that uses a rubber band on the outside of the barrel to pull the sliding compression chamber against the breech to compress air.

Quiackenbush Lightning
Quackenbush Lightning uses rubber bands to pull a sliding compression chamber against a barrel to compress air.

Keep it honest

While we will allow catapults, I think we will draw the line at percussion caps and primers. They are explosives that turn our airgun into a firearm. Let’s see if we can avoid that.

Contest?

I would like to turn this into a contest. The winner would be the niftiest design that the most people could build. I’ll look around for something I can award as a prize. I would also like to test your gun, so it’s got to be real.

Go to it, guys! You don’t have to submit an idea today. How about shooting for the end of September?

100 thoughts on “Design an airgun


  1. I think those potato guns / spud guns are dangerous because they typically involve igniting some kind of “fuel” like propane, gasoline or even hairspray. If the explosion is too strong, the whole thing might blow apart.

    But maybe this PVC pipe thing isn’t such a bad idea afterall. I’m thinking of something like a single-stroke pneumatic.

    If we take a PVC pipe and design a pump head for it, plus some kind of cocking mechanism, all we would have to add is some kind of valve/trigger that opens quickly plus a barrel.

    If we take a large pipe, it could double as a stock. Another idea might be to make a wooden stock/cocking linkage and use that to compress air in a smaller pipe. Maybe metal pipe would work for this purpose as well.

    EDIT: Since bicycle pumps are cheap and readily available, we could also make a multi-pump. That would eliminate the need for making a pump head.


  2. B.B.,

    What comes to my mind is using a cheap slim pocket bicycle pump adding rubber bands to the pump handle to slam it close and a barrel (maybe a length of metal tubing?) on the output chamber. Maybe I can fashion a sliding cover to make it a breech loader or non at all making it a muzzle loader.

    Siraniko


    • Siraniko
      I got a idea.

      Let’s take a air tube that has a one way check valve on it and hook up a tire pump to it and pump it up to say 80 psi.

      Then let’s make a valve with a very light spring to hold a check valve closed till we want it to open. Then let’s make a striker that can hit the valve stem open and transfer air to the barrel.

      It would only get one shot per 80 psi fill. The next question is what would the projectile be made from and what shape.

      Do you think it would work?


  3. BB,

    This is a right interesting little project, superb for a bunch of people about to lose it from social distancing and sheltering in place. Why not put those squirrely brains to work? Who knows, maybe an airgun company will be watching and use a couple of the ideas. No credit given, of course.


  4. Hank,

    On the subject of big bore airguns you say that you do not like them primarily because of the low shot count. Discounting the fact that you could probably club to death one of those deer in your yard with this long air rifle, how many shots do you need to kill a deer? Almost every single deer I have killed, I have done with one. The exception was one I shot behind the shoulders and I had to shoot it again to put it out of it’s misery.

    How many shots do you need for a hunt? You are not going to shoot squirrels with this thing, not if you hope to have anything left to eat.


    • G’morning RR,

      It’s not that I don’t like big bores it is just that I don’t think that they are practical. No doubt that they can take down big game but I look at them more as a novelty than anything else. Guess that in certain areas (like where powder burners were restricted) they would be a reasonable option.

      Shot count is not the issue for hunting (I rarely needed more than one arrow to fill my tag) but for general shooting having to be tethered to a tank or stopping to refill every couple of shots would get old for me very quickly.

      I would love to have a big bore to tinker with and experiment with different bullets. They have a way-cool factor but I kinda see them as a “how big can I go” project to explore the limits of the technology. Sorta like pumpkin cannons and launching anvils.

      I am not against large caliber airguns, its just that a 30 fpe, .22 caliber is plenty of power for the pests and small game I hunt. Just like archery, I have compound bows and a crossbow but my favorite hunting bow was a 50 pound ironwood (hophornbeam) that I made. Guess that I am saying that high power doesn’t attract me.

      Cheers!
      Hank




    • You mean Jörg Sprave and his Slingshot Channel? “Let me show you its features… HA HA HA HA” 🙂

      I just found that channel a few days ago and now BB proposes a project like this…


      • Yea, this could get interesting. My first thought was PVC. Then it was rigging up one of those big jerky shooters with a spring and a barrel. This topic could really , really take on a life of it’s own.



  5. So, are we going to ignore co2?
    There is a lot of volume in a 12gram cartridge once it expands.

    The Girandoni Air rifle used a .46 caliber ball, at about 800psi. To generate about 500fps.
    (A .457 round ball weighing about 143grains)

    I think a copper tube, of your chosen caliber, with a rear expansion chamber. (Not so large that you lose a lot of pressure)
    Pierce the 12gram cartridge to have the liquid co2 expand to gas,

    Then a fast dump valve to dump the entire co2 charge behind the projectile.



    • Bravo
      You ever take a small diameter tube about 10 inches long and put about 4 or 5 bb’s in it and blast some air in it with a air nozzle from a 150 psi shop compressor?

      A little warning ahead of time. Don’t put your hand in front of the tube before you blast it with air. I promise you won’t like the results.


      • I used to shoot AA batteries out of copper tubing using 125psi shop air.

        And have made several bb machine guns using 125psi shop air nozzles & brass tubing and a hopper for the Bbs.

        A poor mans shoot the star tommy gun from the county fairs.


        • Bravo
          Remember Milk Duds I think they was called.

          We shot those and jaw breakers candy out of steel pipes like they use on natural gas lines for your house with shop compressor air.

          They will send them flying pretty hard and the jaw breakers woud dent a old galvinized trash can they use to make at 50 yards.

          It don’t always have to be 3000 psi to make a air gun work.


          • Like the cork gun shown, we used to use 2 pieces of bamboo thAt would fit inside each other, put a chinaberry into the larger one, ram it forward a little, the insert another to act as the piston and rear seal.

            tpush the smaller Bamboo into the other one, as the air compressed, it shot out the first berry.

            Then the second was ready to fire. Just insert another chinaberry and do it again, and again.




  6. I have both pneumatic and starting fluid fired potato guns. There is a big difference in the energy produced between the two. The pneumatic is by far more powerful. Runing on air the pneumatic has more than twice the power of the ether gun.

    I’m guessing the ether gun develops around 30 psi. It has a loud pop when shot. So it is still building pressure as the projectile exits the muzzle. It has a piezoelectric striker for the trigger making it easy to hold on target.

    The pneumatic has more of a whoosh as it is shot. I have shot it up to 100 psi. It has a simple ball valve making it hard to hold on target. An automatic sprinkler valve can be used for a better trigger system.

    There was rifled PVC for sale a few years ago. I don’t see it anymore and didn’t try it.

    They are not restricted to potatoes for the projectile.

    The simplest pneumatic gun I made was a 22 caliber pellet gun. It was a Maximus barrel hooked to a compressor blow gun for the trigger. It had pretty good power at 100 psi. I think deep seating the pellet was the trick for good velocity.

    Don







            • Chris
              I did check it out. And it is in a sense a air venturi. It changes presure in the tube.

              Tell me what you think would happen if he placed a restriction in his tube somewhere?

              It will speed up the air flow be it vacuum or pressure.

              And maybe later Shootski or some one else can do some searches about airflow and tell us what restriction does to air flow.

              Matter of fact what do you think a transfer port in a airgun is. It is a venturi. It doesn’t have to be a liquid. It can be a gas as in oxygen and such.

              And guess you didn’t do much tuning on dual carb enjgnes have you.


              • Gunfun1,

                Don’t need to look it up: Bernoulli!

                In fluid (compressed gases are considered to be fluids) dynamics, Bernoulli’s principle states that an increase in the speed of a fluid occurs simultaneously with a decrease in static pressure or a decrease in the fluid’s potential energy. The principle is named after Daniel Bernoulli who published it in his book Hydrodynamica in 1738.

                It sounds like what you want but in our airgun case it isn’t the speed or even the pressure directly but the Mass FLOW that gets the power behind the projectile. It is actually F=ma that is what it is all about. In a PCP it is mostly the m (Mass) that gets the F (Force) and in Springers it is the SUDDEN! a (acceleration) part of the equation that gets the typically much lower Mass projectile to move at speed.

                Getting a NACA vent into the airgun TP (Transfer Port) role is so much much better of a way of developing a great deal of FLOW; just really difficult to design and fabricate! Gunfun1 you know! Just like on the cooling inlets on aircraft and race cars!

                shootski





          • Don
            The barrel wouldn’t need to get smaller. Somewhere before the barrel would have the restriction.

            It would become harder to cock I guess we would call it. But its all about a balance of cocking or the extra power you could make with the venturi. The size of the venturi diameter and length and angles would need to be experimented with to get it efficient in both ways. Cocking and speed of the projectile.


          • Don,

            As I recall,.. it was like a giant syringe. Hold your finger over the end and pull back. After a couple of versions,.. he had a long pull back rod. On the front of that was loaded a projectile, prior to pulling back. A light cover over the end of the barrel further insures vacuum integrity. When the pull back rod rod was pulled back (and held back) the vacuum was vented to air at a point between the end of the rod and the (back) of the projectile. The pull back rod never moves, but the in rush of air shot the projectile out the end of the barrel with great force.

            Chris


        • I just remembered there are formulas for the reservoir volume vs the barrel diameter and length for the potato cannon. They may be adaptable to the vacuum cannon with a smaller barrel in front of a larger vacuum reservoir.


  7. B.B. and nascent airgun designers,

    I was reading the blog and kept thinking about Holdbacks that are used to ensure the catapult stroke is powerful enough to launch the aircraft safely at the actual weight. The Holdback is a dumbbell shaped machined piece of steel with known tensile strength that is set by machining out a break point to the correct diameter. The one end is inserted into the Cat’s shuttle and the other to an attachment arm on the A/C nose gear strut. It ensures a small SD for every launch! But that is a pretty diddly system for an airgun.

    So i decided to think some more…

    and up popped a Burst Disk (rupture disk) method of simple consistency of bullet launch charge.

    https://en.m.wikipedia.org/wiki/Rupture_disc

    http://www.bsbsystems.com/Rupture_Disks/rupture_disks.html

    I envision a 500psi (3447.379 kilopascals) pressure vessel(s) and a vacuum pump attached to the barrel about 3′ back from the muzzle to get pressure below 6 psi (34.474 kilopascals) in the Barrel. The barrel muzzle would need a piece of mylar tape to hold vacuum and then as the round approaches the muzzle the residual air in the barrel would blow off the piece of tape and not effect accuracy. With a revolver system you could get a multi-shot air/vacuum weapon of some number of rounds. I believe after some back of the envelope calculations that it could easily provide 400+ FPE with the right choice of projectile!

    Materials could be small 1800psi Catalina cylinders, Burst Disks, seamless hydraulic tubing of various diameters and a smoothbore barrel of the proper diameter (which could be rifled) after early developmental testshowed actual performance in MV FPS.

    Very much a KISS approach and relatively inexpensive in design cost and fabrication!

    shootski


  8. I just remembered my daughter had a science project in high school to build a pingpong ball shooter. They had to hit a little ship in a wash tub at a given distance. I forget the distance. Of course I found out the day before it was due.

    We built a spring piston gun out of a cardboard tube that had an od that fit the pingpong ball. The compression cylinder was an oatmeal container. Round cardboard. It was mounted on a piece of 2 x 8 board. The piston and connecting rod went to a lever hooked to a spring. The spring was mounted below the connecting rod to increase the piston velocity. I think the piston was cut from a piece of plywood. We had to block the lever so the piston stopped before it hit the end of the oatmeal tube. Or it would tear itself up. We used a screw Jack to adjust the elevation and made some sights. We sighted it in for the distance she had to shoot. I forget what we did for a trigger but it had one. Just letting go of the lever did not work.

    Each student got two shots at the ship. I think she was the only one to hit the ship and she hit it both shots. By the time she brought it home they had shot it till it fell apart. That was before cell phones so we did not get a picture.

    Don





        • Don,

          Without doubt,… such controversial activities would not be permitted in today’s schools. Re-enactment of land to sea warfare!,…. oh my! Not to mention the launching of any sort of projectile. A spit wad and a straw would probably land you hitting the skids, sitting on the curb, waiting for mom and dad to pick you up after getting suspended for the year. Doomed. A bum for life.

          Whatever happened to Robot Wars on TV????? How cool was it to saw your opponent in half,… then smash each half with a 10# sledge,… and then for the finale,…. toast them with a flame thrower????

          Now that is what I call reality TV! 🙂

          Chris


  9. There are electric kettles that can boil almost 2 liters of water in only a couple of minutes.
    http://www.megachef.com/products.php?cat=electric_kettles
    How about using a very small battery operated sealed electric kettle in an airgun. A very well sealed small sized kettle that uses only a little amount of water and can produce enough steam to propel a BB? Before every shot, the air gunner adds water into the airgun and waits for the water to boil – takes about a minute. When the steam produces enough pressure in the kettle, the shooter gently pulls the trigger – and the trigger sprays enough steam into the barrel to propel a BB. The kettle could be small enough to be built in the buttstock; the seal had to be very strong, safe, and etc… I don’t think this can be safely built by the readers though, so don’t try this at home.


    • Steam,

      Pure brilliance! I could see that working. After all,.. steam has provided plenty of power to blowup standing boilers and locomotives in the past,… eh? Not to mention a (plugged) moonshine still or two!

      Chris


    • Steam,

      As long as the system is tested and has a pop off valve it should be safe for many folks, not all but many. The need for more power is the problem. I like the idea. It could even run off an extension cord if the battery has too many limits. The lipo batteries sure carry the watts though. A good reason to go back to a brass airgun to reduce corrosion.

      Don


      • Don,

        I would go PVC pipe, hot plate, kettle fitted to PVC,.. and a varied layered amount of aluminum foil for a burst disc. Foil,… not for safety,..but for sudden burst of steam to launch a projectile.

        When,.. WHEN the foil disc would burst,.. that would be the trigger. “Ok,… this bugger has a ton of power. It will fire at 1-2 minutes. Ok,.. maybe 3. The longest I have seen is 4. 5? Uh,.. maybe we had better step back a bit” 🙂

        A greased up stress squish ball in some PVC would be perfect.

        Chris



    • Steam,

      You may have something in that concept! I bet it would be a hit in the UK! After the shoot you use what’s left in the kettle to brew some PG Tips and we all sit around have a Cup a’ and gab about our accuracy!

      shootski


    • I visualized the kettle boiler no bigger than a CO2 cartridge, so that a battery operated heater would be able to boil the water inside without needing so much power – a single shot design… Something made of steel alloy, pretty much a miniature boiler / electric kettle. That steam power plant could be built into a CO2 rifle – after a lot of alterations and modifications, considering there would be water and steam involved.


      • Steam
        Maybe that could be a good survival gun for shooting some food when other things like rubber seals and stuff don’t exist anymore to pump up your pcp gun.

        You could put the cartridge in your camp fire for a bit then load it in the gun and shoot. Maybe not as simple as that. But you know what I mean.


        • Gunfun1,

          That puts a new spin on the saying get it while it’s hot. Maintaining the pressure requires keeping the steam hot. Either you have a heat source or your container is a vacuum flask.

          Siraniko


      • A glow igniter from either a gas oven or dryer would work as your heat source. Might even heat up using battery power (car or an old forklift battery). That way it would be portable, sort of.


      • Second thought, in case the water is poured into a CO2 cartridge sized miniature boiler, I think the water can be boiled by vacuuming the air in the bolier. Air gunner fills the little bolier halfway with water and then uses the pump on the rifle to vacuum the air in the boiler. Water can be boiled without heating by increasing the pressure on the surface of water inside a closed insulated vessel. By doing so, the boiling point of water can be decreased to room temperature. After quickly removing enough air from the steel alloy boiler, the boiling temperature will fall below the water temperature and boiling will begin without heating. The rifle could have a pump just like the Avanti 753S has. There is no need for batteries or miniature kettles after all, just add some water into the rifle and pump the lever a few times / even single stroke could do the job, who knows…


  10. Ok,

    I think a semiautomatic plinker bb gun runing on compressed air 100 psi is easily doable. The gun should hold at least 500 bbs. The tether can be very flexible and small paired to a small plenum.

    Don


  11. 70+ comments mostly talking about this challenge. Impressive. How many are actually going to take up this challenge?

    I’m not able. Hope some that shared insights and theories will act since I for one would find their entries fascinating.


    • Kevin,

      I already submitted mine. A soda straw (Eco-friendly stainless steel,.. of course) and a sheet of paper. 95% of the paper is printed with the word “ammo” and the other 5% reads “if you have to ask,… return straw and paper to box and get a refund”. $9.99 with free shipping. Additional ammo packs with 5 sheets of ammo for $4.99 each. In Walmart this Fall.

      😉 Chris


  12. Just read about a kid attending video school who had the police called on him for having a toy gun in the room with him on camera So lets make it clear this is an adult project.

    I had a PVC bazooka looking shoulder mounted air gun that fired just about anything that you could fit in the center of a hard foam cylindrical shape sabot that was cut into 4 pie slices and held together with tape at the back. It spread open and fell away right after it left the barrel and the projectile inside it continued down range as intended.
    It used a foam coffee cup, cut just about in half to fit inside the barrel, and it acted as an air seal. It also was ejected when fired and dropped away.
    It could put a half inch diameter steel bolt through 1/2″ plywood using a 100PSI air charge. It would also shoot anything that fit into the barrel. A ball of masking tape might knock you on your butt if it hit you.
    It consisted of a air reservoir tube around 2 to 3″ in diameter and a smaller diameter barrel tube. They were connected close to the rear with a 9V battery operated PVC sprinkler valve.
    A much smaller tube attached with a hose clamp held the battery and fire button, clamps also held the tubes together with wood block spacers in the front area and a heated soft section of PVC was squashed and glued to the bottom as a grip. The other hand was used to push the button on top to fire it. Although it could have been incorporated into the pistol grip. A plastic rail was glued to the barrel tube for any type of sighting optic you desired. I used a cheep 4X10 scope.
    An awesome thing to behold and hear … VAROOM ! Painted up to look real and it will immediately expose any off duty law enforcement that may be present at a BLM shooting range.
    Now it may be more of a cannon looking air gun but the operating principle may be reduced in size for pellets. It was the immediate release of a large volume of low pressure air 100PSI (Small foot operated bicycle pump ) and use of a carrying sabot that did the trick.

    Almost forgot the sabot with projectile and foam coffee cup seal were inserted into the back end of the “Barrel.” It had a screw on end cap. A small PVC tube was glued to the inside of the end cap to push the seal etc. far enough forward to clear the air transfer port from the air reservoir.

    PVC, glue, 9v sprinkler valve & battery with fire button. sighting optional. It originally had a small PVC tube for a sight.
    Bob M


    • BB
      Failed to wish you a happy birthday, but now that we are both 73 I feel compelled to fill you in on my experience, I went to the emergency room early this month suffering from dehydration and heat exhaustion, I suppose, after a week of over a 100 degree temps. All tested well with an IV inserted but my BP was 214 over 95.
      My symptoms led the Doc to do more tests, CAT SCAN & MRI , for more serious conditions. He returned to my room in a huff and demanded to know why I was ‘not’ taking aspirin since I had suffered a stroke a while back. “News to me” I replied. Turned out to be in the back of my head in an area that controlled balance but no symptoms ever evolved. Aspirin and cholesterol meds are now mandatory for precautionary measures.

      Just lived through a week of over 100 degree weather with no electricity and a 17000 acre brush fire threat.
      The Valley Fire in San Diego east county. Don’t know if my generator can take any more 7/24 use or my body can survive without sleep like that again 🙁
      Bob M
      By the way… the left news reports the fire was caused by climate change and it may be true. It was a very small climate change that occurred around a tractor that caught on fire.


      • Bob,

        Wondered how you have been. Glad you survived thus far. I have been following the fires on the news (from Ohio). “Apocalyptic” is the news’ favorite word. I would have to agree from the videos.

        Climate change? Maybe. Maybe not. Not clearing/controlling the land/brush/trees seem to be more likely. They cited “tree huggers” for a lot of the clearing opposition. Even if done,.. that is a lot of time and money spent by the state/local governments to do so. Even if you have your property in good order, it would not matter unless the neighbors/entire neighborhood did the same.

        Good luck with the generator holding up. The worst part is feeding it. My Dad had a cheap 3000W and my sister’s family needed it for 10 days 24/7 and it is still running fine. I have a 2000W Honda that will run 9 hrs. on 1 gallon at idle. Then again, it only holds 1 gallon. I would think that car engine air cleaners would be taking a hit too with all the soot.

        Hang in there bud and keep us posted,………. Chris


      • Bob M,

        Very sorry to hear about the extremely challenging conditions you’ve been put through. I wish you the best as we continue to hunker down across CA and wait things out.

        WD


      • Bob
        I seen some pictures and it’s like the sky and everything around is all red. I can’t even imagine how hot it is.

        Praying that it will get under control and be over.

        Lot of crazy stuff happening this year.


      • BobM,

        Glad you have come through the troubles so far!
        I Pray that nothing you can’t handle or effectively deal with rears up in the near future. My son explained the situation intention back burn to his neighborhood in Millcreek Utah when they had a fire one ridge east of them stop just before it started down toward them. He told them that if they didn’t clean up their properties the next back burn might include their properties! They have banded together to do the needed work.
        It always kills me when people talk about the cost of forrest/wildlands fire remediation actions…and then you see the cost of the replacement burntout homes, burntout firefighting equipment, burn injury injury care not to mention lives lost.

        Stay safe and drink more fluids… doesn’t need to be water….

        On that PVC tube Bazooka i replaced it with thinwall seamless tube and replaced the endcap with a metal one and cut out the threads so you could open the breech with a quarter turn. I wish i could have done the kind of breech plug that the BB’s 16″ rifles used.

        shootski


  13. Appreciate the replies. All is well for now.
    The Sierra Club out here in CA will not let anyone properly manage forests to reduce major fires and they are hand in hand with the politicians who blame people for causing climate change they wish to blame it on.
    Fire is a natural occurrence out here. Some seeds require it to grow.
    People and forests should not mix. Pass through it and visit for a while but don’t live in it.. High, dry, winds cause the fires to get out of control.
    We work with our local fire departments to reduce the chance of fire spreading through peoples property, in the brush zones, with vegetation management rules based on distance.

    The practice of waiting for a fire to get to certain place to tackle it is gone. Kill it ASAP with everything you have is the new rule now . Seems they forgot to keep the access roads clear of growth.
    Bob M


  14. Well, I have one for your contest. This is one that started out as a .410 CO2 shotgun that I designed. It is based on a QEV type valve, rather than the hammer fired poppet valve. Since most commercial QEV valves are rated at about 150 psi, I had to design one that would work safely in the 1000 psi area that I wanted to work in. Most of the “plumbing”, including the QEV, in the gun is made from fittings with at least 1000 psi working pressure. The gun has since been updated to a 9mm rifled barrel, with a 13 cu in HPA tank. With the regulated air, it charges a plenum up to about 900 psi, and the trigger vent valve fires the QEV valve and dumps the plenum out through the barrel. By changing the plenum size, you can control how much gas is used. It currently gets about 57 FPE with 82 grain .357 pellets, and gets 10 shots per fill.



  15. Here’s a little more info on my entry. Here’s a 5 shot string with 82 grain pellets:
    583
    593
    578
    561
    577
    Average = 578.4. 60.93 FPE
    Here is an “exploded” picture taken during the development phase. The physical configuration is somewhat different than the current, but the parts are pretty much the same. Remember, safety is a must when dealing with high pressures. All of the parts used here have a working pressure of at least 1000 psi!




    • Doug,

      Laughs?,… you are killin’ it! A bit heavy on the steps,… but it works and,.. you have a video!

      Do you even know what it is you will win? It (was) revealed when I made a comment to BB.

      Chris


Leave a Reply