a compressed gas powered gun provides recoil simulating the recoil of a gun firing gunpowder propelled projectiles . the valve assembly provides both consistent shot to shot pressure , and rearward gas pressure for generating recoil . preferred embodiments of the compressed gas powered gun may include means for adjusting the amount of recoil provided . a trigger mechanism permitting semi - automatic operation , or full automatic operation at a user selectable cyclic rate , is provided . the air gun provides consistent gas pressure behind the projectile from shot to shot . a magazine and magazine indexing system for loading projectiles into the firing chamber in a manner contributing to the accuracy of the air gun is also provided .