US Patent 7775149 Action rate control system

An action rate control system for a gas operated firearm that includes an action sleeve and an action rate control cylinder. The action sleeve moves in a rearward direction in response to a volume of combustion gases that are generated during firing of the firearm and diverted from the barrel of the firearm through gas ports. The action rate control cylinder is connected to the action sleeve by a linkage that controls movement and slowing of the action sleeve as it approaches a rear limit for its movement. The resistance force generated by the rate control cylinder is a function of the velocity of the action sleeve during its movement. In another aspect, a gas operated firearm includes a barrel, a bolt assembly, an action system coupled to the bolt assembly, and a rate control cylinder coupled to the action system. The action system includes a sleeve assembly that is driven by a volume of combustion gases that are diverted from the barrel when a round of ammunition is fired. The rate control cylinder controls a terminal velocity of the sleeve assembly being driven by the volume of combustion gases. A resistance force generated by the rate control cylinder is a function of the velocity of the bolt assembly during the bolt assembly's rearward movement. The velocity of the bolt assembly follows a controlled and gradual reduction as the energy load associated with the firing is absorbed by the rate control cylinder.