Pneumatic arms

Discussion in 'FirearmsTalk Support and Suggestions' started by alhefner, Jul 9, 2009.

  1. alhefner

    alhefner New Member

    112
    0
    0
    You guys have a great site and I love the legal and RKBA forum.

    My other interest though lie in pneumatic arms. They are not classified as firearms but things are progressing to the point where a good PCP (pre-charged pneumatic) of sufficient caliber can be used even for deer hunting!

    A forum on that topic would be of great interest to me as I am trying to find methods to make these interesting arms more efficient than they already are.

    What do ya'll think? A forum here for pneumatic arms? Everything from .177 to .50 is already out there and available.
     
  2. c3shooter

    c3shooter Administrator Staff Member

    21,445
    557
    113
    Not really into the pneumatics, but FWIW, ever hear of Isiah Lukens? Built the .31 cal air rifle that Lewis and Clark took with them in 1803. Stock was a hollow metal air tank, held full charge at 900 psi.

    Again, that was 1803.
     

  3. orangello

    orangello New Member

    19,156
    0
    0
    Interesting, i actually picked up a neat little daisy pump up pellet gun the other night (.177 i bleve) for less expensive plinking.
     
  4. alhefner

    alhefner New Member

    112
    0
    0
    Yeah, I got a .177 co2 repeater pistol and .22 cal co2 rifle just for the fun of it. Cheap plinking!

    My interest I guess is now turning technical. All pneumatics, except for the "spring - piston" variety, suffer from the same flaw. Once the trigger is pulled the forces pushing the projectile rapidly decrease as the projectile moves down the barrel. With powder burners, it is possible to maintain pressure or even have it increase behind the projectile until it exits the barrel depending on powder used.

    I am trying to come up with methods to minimize the actual decrease of pressure that happens in pneumatics.

    Not looking to make them push a bullet like a powder burner does but simply improve efficiency. Got no problem with keeping things subsonic.
     
  5. orangello

    orangello New Member

    19,156
    0
    0
    I wonder if they could use something like the "gas port" on my SKS, only in reverse and timed to release more pressure after the projectile passed the port?
     
  6. alhefner

    alhefner New Member

    112
    0
    0
    Right now, most pneumatics have a sort of "timed release" via basic mechanical means. The tube that transfers the air / gas pressure is attached to a block that is spring operated. The tube has small holes in the rear portion to allow air / gas into it. After / during cocking, which moves the block and tube rearwards past a seal, a valve opens that allows pressurized air / gas into the pressure chamber forward of the seal. When the trigger releases the sear, the tube / block assembly moves forward so that the holes in the tube are forward of the seal and allows pressurized air / gas to enter it and on into the barrel behind the projectile. Right at this point, there is maximum pressure that drops rapidly as the projectile moves down the barrel thus increasing the space the air / gas can expand into.

    Hope that is understandable!

    Any way, I am thinking of a couple of things.

    One is simply to enlarge the chamber where compressed air / gas is held thus having a larger volume to start with.

    Another would take some real engineering! Some very strong spring-piston device that is "loaded" by the compressed air / gas itself. As the air / gas is expelled, the spring would push the piston into the chamber to ensure minimum loss of pressure. I know that on co2 guns, as long as there is liquid co2 left in the cartridge you will have about 900 psi available. A setup like this could accomplish two things. One, if set up to "cock" at a minimum of 850 psi then the pressure behind the projectile would drop very little. Two, it could really be a safety feature since the gun would not arm if there is not enough co2 left to cock it. Hmmm....now, I am thinking it could work a revolving cylinder too like my .177 pistol has!
     
  7. divinginn

    divinginn New Member

    207
    0
    0
    I wonder what you could do with a 3000 psi scuba tank,they make some very small lite tanks. That sounds like a good project,I have 5 scuba tanks laying around. It would be neat to build one about 22 cal.
     
  8. orangello

    orangello New Member

    19,156
    0
    0
    I wonder if barrel temperature could be used to maintain pressure, something like a heating coil around the barrel.
     
  9. alhefner

    alhefner New Member

    112
    0
    0
    They are already using scuba tanks to recharge PCP arms. They use the scuba as "mass storage" for up to 3500psi then use it to charge the PCP rifle or pistol. These are available in .177, .20, .22, .25, 9mm, .45, and .50. Most charge to 3000psi but Crosman is offering the Benjamin Discovery that only charges to 2700 psi.

    As for heating the barrel, it's a thought. With CO2 you have to be careful not to shoot too quickly so you don't cool the rifle or pistol so much that you get a significant drop in pressure. I can easily demonstrate that with my 8 shot repeating Crosman CO2 pistol!
     
  10. IGETEVEN

    IGETEVEN New Member

    8,358
    4
    0
    Indeed, that is a great idea, but you do not want to be mistaken for these guys, they had almost the same concept. :D
     

    Attached Files:

  11. orangello

    orangello New Member

    19,156
    0
    0
    ^^^ Those guys look more like the guy in Predator with the minigun & ammo backpack.


    Re heating: They use bottle warmers on the nitrous tanks for drag racing.
     
  12. RL357Mag

    RL357Mag New Member

    3,250
    0
    0
    These guns already exist. An older issue of Shotgun News did an article about .30 cal. and 9mm air guns that have sufficient velocity and energy to take deer. They are pre-charged and have pressure gauges. They are also more exoensive than their centerfire counterparts. Also, I believe air guns are classified as "firearms" in NYC and Massachusettes..
     
  13. alhefner

    alhefner New Member

    112
    0
    0
    I am fully aware that they exist and are already used for hunting game up to deer. An yes the Pre-charged pneumatics are nothing new. What I am interested in is getting discussions going on improving them and making them more efficient at the use of the charge of air or gas (CO2).

    Yep, in some states air powered rifles and pistols are classified as firearms and regulated accordingly. Just check out Cabela's or Pyramyd Air and you will see the restrictions some localities have on them.

    Current popular calibers used for hunting with pre-charged pneumatics are .22, .25, 9mm, .45 and .50. The .30 does exist and is made in limited quantities mostly by custom rifle makers.
     
    Last edited: Jul 10, 2009
  14. N.D.

    N.D. New Member

    154
    0
    0
    I read articles on some of these i years past but I lost my info on them so ... Can any one provide any links to some of these air guns they still sound very interesting and I would like to revisit them?