US Patent 7878184 Hardball weapon

A hardball weapon for use in exercises or shooting games and designed as military gun is made with a weapon housing (3) containing two coaxial pistons (21, 26) which are mounted directly in the weapon housing (3) and driven by an electric motor (10) via a gear wheel mechanism (12, 18) and toothed racks (24, 25). The first outer piston (21) functions as a movable bolt for loading the cartridge chamber with cartridges (7) with solid balls (6), and the other piston (26) functions as a pressurised air piston for creating an overpressure for firing the balls (6). The weapon housing (3) can be opened by pivoting, thereby giving access to the parts in the firing mechanism for inspection, repair and adjustment.