lb ) [1] Length 640 mm (25.2 in ) stock extended [1] 470 mm (18.5 in) stock collapsed Barrel length 260 mm (10.2 in) [1] Cartridge 9x19mm Parabellum , .22 LR , .45 ACP , .41 AE Action Blowback [1] Rate of fire 600 rounds/min [1] Muzzle velocity 400 m/s [3]