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PSI in a pellet gun?

Discussion in 'General Gun Discussions' started by heisler, Jan 13, 2006.

  1. heisler

    heisler Well-Known Member

    What kind of pressures do pump-up BB/pellet guns like the Crosman Pumpmaster 760 work at?
  2. MrTwigg

    MrTwigg Well-Known Member

  3. Crosshair

    Crosshair Well-Known Member

    My air pistol has a brass barrel so the pressures can't be that high.
  4. heisler

    heisler Well-Known Member

    Yeah, I'm thinking it has to be a good deal less than 3000psi. That's what the SCUBA-powered guns use, and they can get off quite a few shots before needing a refill. Potato cannons only need 100psi or so. I'm just curious about this because I like to occupy my time by building imaginary airguns in my head. :)

    Thanks for the link, MrTwigg.
  5. slopemeno

    slopemeno Well-Known Member

    Since most airguns have a similar C02 model to match the pump model (i.e Benjamin Sheridan) I would guess around 1600 psi pumped to the max. It is possible to pump a Benjamin-Sheridan to the point that the valve cant discharge. If you guys are interested in this stuff "Mac-1" does tons of mods on the american made airguns.
    The high end 3k psi bulk fill guns probably dont deliver that to the valve anyway. It would be interesting to find out just how high the pressure goes in a high-end springer, since theres quite a bit of heating of the air column going on there.
  6. KriegHund

    KriegHund Well-Known Member

    highest ive seen was in a GAMO, 1200 FPS.

    Thats higher than some larger caliber pistol cartridges.
  7. Hawkmoon

    Hawkmoon Well-Known Member

    FPS is feet per second.

    That's velocity, not pressure.
  8. Ol` Joe

    Ol` Joe Well-Known Member

    They`re obviously not for kids anymore.:what: :what:


    The most I`ve seen noted in a air powered rifle was 3000 psi. I don`t know if others have a higher rateing but I believe most run ~1000 psi as max for a common hunting Beemen or other spring type.
  9. Billll

    Billll Well-Known Member

    One of our people contacted the Daisy company about the CO2 cartreges, and found that they contain liquid CO2 at 900 psi. The guns that use external tanks at higher pressures, likely have a regulator, or a plenum chamber to bring the high tank pressures down to something more modest.
    Muzzle velocity will not be proportional to chamber pressure. You can drop a lot of pressure before losing very much velocity. Barrel length and valve dynamics figure heavily into this too. Hand pump guns will be working below 900 psi, generally.
    Pressure in the barrel can be approximated by using F=MA, where M is the mass (not weight) of the projectile, and A needs to be calculated based on 0 to muzzle velocity in (length of barrel). X = 1/2 At^2, V = At, solve for A
    Solve for F and divide by the cross-sectional area of the projectile to get PSI in the barrel. Max P in the barrel will be a bit higher than this, as pressure drops off as the projectile goes down the barrel.
    I like guns for the physics of the things.

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