A gas powered gun has a gun barrel, a cylinder containing a primary piston moveable between a loading position and a firing position, a secondary piston moveable within the primary piston between a loading position in which the leading end of the secondary piston is sufficiently withdrawn in the barrel to permit a projectile to be fed into the barrel through an opening in the side thereof and a firing position in which the secondary piston has moved forwardly to cause the leading end of the secondary piston to engage the projectile and move the projectile forwardly in the barrel. A trigger is operable to cause the primary piston and the secondary piston to move simultaneously from the loading position to the firing position. The cylinder has a chamber through which the primary piston and the secondary piston extend. A pressurized gas supply supplies pressurized gas to the chamber when the primary piston and the secondary piston are in the loading position, the primary piston and the secondary piston isolate the chamber from the pressurized gas supply when the primary piston and the secondary piston are in the firing position and cause pressurized gas from the chamber to be ejected from the leading end of the secondary piston to fire a projectile from the barrel. Thus, movement of the secondary piston between the loading and firing positions has two components, one component being movement with the main piston and the other component being movement relative to the main piston.