Abstract: An automatic projectile firing weapon and a related method for absorbing the recoil force of an automatic projectile firing weapon are disclosed. The weapon includes a barrel assembly that is slidably mounted in a receiver, biased by an operating spring, and engageable with a main sear. A gas operated bolt assembly is slidably mounted within the barrel assembly and is driven by a bolt spring. A trigger is provided to release the main sear and allow the operating spring to move the barrel assembly forwardly in the receiver. There is further provided a buffer connected between the receiver and the barrel assembly to dampen the velocity of the barrel assembly to ensure the barrel assembly is moving at a predetermined maximum velocity when a round is fired at a predetermined firing position. The recoil energy from the fired round is absorbed mainly by the forward motion of the barrel assembly and in part by the operating spring and buffer.

Abstract: An ammunition indexing mechanism for moving, responsive to actuation of a trigger mechanism, a cartridge from a selected one of a pair of opposed feedports in a weapon receiver and into alignment with a firing chamber of a barrel assembly of the weapon, has a rotary mechanism for moving through a selected index angle each ammunition cartridge entering through the selected feedport; and a torque assembly for storing energy, responsive to a selected movement of the barrel assembly, until released to operate the rotary mechanism to move, for each selected barrel assembly movement, each sequential cartridge through similar angular displacement to a position aligned with the firing chamber.

Abstract: A novel mechanism for moving a gun bolt toward and away from a firing chamber of a barrel assembly having movement relative to a receiver in a cartridge-firing weapon, having a camming channel formed in the receiver of the weapon, uses a rack member having an end coupled to the gun bolt and moving substantially linearly with the gun bolt toward and away from the chamber. A gear train has a housing affixed to the moving barrel assembly; an input member moves in the camming channel responsive to barrel assembly movement, to cause an output member to move the rack member and attached gun bolt toward and away from the chamber with substantially-linear displacement, velocity and acceleration greater than the associated displacement, velocity and acceleration of the moving barrel assembly with respect to the weapon receiver.