Patent ID: 8418389

Claim:
A weapon, comprising: a housing; a receiver translatably disposed in the housing; a barrel having one end fixed to the receiver, the barrel being translatable with respect to the housing; a spring stop fixed to the barrel forward of the housing; a spring disposed between the spring stop and a front of the housing; an operating group translatably disposed in the receiver; a gear rack fixed to the operating group; a longitudinal member having one end fixed to the operating group; a counter-mass having a second gear rack and an opening, another end of the longitudinal member being translatable through the opening in the counter-mass; a second spring disposed around the longitudinal member, one end of the second spring bearing against the operating group and another end of the second spring bearing against the counter-mass; and a pinion gear rotatably fixed to the receiver and operable to mesh with the gear rack and the second gear rack.