Abstract: A hammer mechanism for an automatic gun has a hammer 742 connected to rotate about a pivot rod 741 and the hammer has a firing pin striking surface 743. A strut 750 is connected by a pivot 752 to the remote side of the firing pin striking surface 743 from the hammer pivot 741 and the opposing end of the strut 750 from the hammer is spring biassed to rotate the hammer toward a firing position. The top surface of the strut 753 is arranged to be tangential to a top surface on the hammer defining a radius 744 so as to enable a block 300 of the bolt carrier assembly 3 to ride completely rearwardly of the hammer and not to foul thereupon on its forward portion of the bolt operating cycle.

Abstract: A sear actuator has a rotatable cylinder (770) mounted between opposing side walls of the receiver (1) and a slidable rod (771) extending transversely to the cylinder. The actuator is arranged so that in one position the trigger applies a rotating force to the sear through the slidable rod (771). In a different position of the cylinder (770) the slidable rod is moved out of the path of the force exerted by the trigger and the trigger abuts a wall of the cylinder and thus the sear is rendered inoperative.

Abstract: A drum magazine for a gun has a circularly cross-sectioned housing (40) with a feed throat (415) extending from the housing for releasing cartridges and concentric sprockets (42, 43, 44) having serrations nesting cartridges. A torsion spring (46) is arranged to rotatingly drive the sprockets and feed ramps (434, 441, 455, 455', 471, 471') are provided for assisting the cartridges to traverse from the sprockets to the feed throat (415).The feed throat has two lips and one of the lips (417) is pivotally biassed to act as a one way valve such that in one position cartridges are prevented from being ejected in a direction perpendicular to the housing axis and yet cartridges may be inserted into the housing in a direction perpendicular to the housing axis.

Abstract: A sear buffer having a U-shaped member with bowed longitudinal arms, the free ends of the arms being arranged to locate a sear therebetween. The U-shaped member is located by a block, a rod and further rod, the bow in the arms being temporarily reduced when the sear is contacted by the lugs of a reciprocating bolt carrier assembly.

Abstract: A fire-arm having a bolt assembly which includes a bolt received by a bolt carrier and axially movable relative thereto and a T-shaped ejector set freely in a T-shaped recess in the bolt and retained in the recess by the bolt carrier while being held axially relative to the bolt by the T-shape of the extractor and the recess. In a first position of the bolt relative to the carrier the extractor is held in a first position in which it engages a cartridge for extraction from the chamber and in a second position of the bolt relative to the carrier the extractor is movable to a second position from which it can move to engage a cartridge.