Abstract: A pre-charged pneumatic air gun includes a barrel, a firing valve, a trigger assembly, a compressed gas storage tank, a first chamber, a larger second chamber and a compression piston movable within the first chamber and the second chamber. The compression piston is operable to increase a pressure in the first chamber to a final first chamber pressure greater than an initial first chamber pressure by sequentially opening a first fill valve with the second fill valve closed to allow compressed gas to flow into the first chamber then opening a second fill valve to allow the compressed gas to flow into the second chamber, thereby displacing the compression piston and further compressing the compressed gas in the first chamber to achieve the final first chamber pressure.

Abstract: A pneumatic gun has a hollow cylindrical bolt which moves in a housing, being spring-biased to a cocked position. The bolt has a pressure inlet which is coupled to an outlet so that, when air under pressure is supplied to the inlet, the pressure and the drag of the air passing through the bolt urges it forward, carrying a projectile into the gun barrel. The air pressure is sustained until the projectile is propelled out of the barrel. A regulator valve reduces the pressure of gas from a holding tank in the weapon to the operating pressure of the control system. The required pressure for the firing valve may be derived from the control system, from a separate regulator, or from the holding tank. In one embodiment, a special firing valve controls the transmission of firing pressure to the bolt. A pneumatic firing control circuit is triggered by one, several, or a continuous series of electronic pulses to produce single, burst, or continuous fire.