Abstract: A belt-fed firearm includes a top cover that can move in at least two degrees of freedom of motion (surge, sway, heave, roll, pitch, and yaw) that in combination allow movement of the top cover to both clear a peripheral accessory mounted to the firearm (such as optics) and open access to a feed surface to permit loading of cartridges to the feed surface.

Abstract: A firearm includes a sear with a sear tip, the sear movable between a stop-fire position, wherein a discharge mechanism is held by the sear tip against movement that would result in firing of a round, and a fire position, wherein the discharge mechanism is released by the sear tip to permit movement of the discharge mechanism to fire a round. The firearm includes a sear return delay mechanism delaying the return of the sear tip to the stop-fire position from the fire position.

Abstract: A trigger assembly for a trigger housing for a, M249 fully automatic rifle is provided having a switch accessible at the outside of the trigger housing for changing the firing of the rifle between semi-automatic and fully-automatic fire.

Abstract: A trigger assembly for a trigger housing for a, M60 fully automatic rifle is provided having a switch accessible at the outside of the trigger housing for changing the firing of the rifle between semi-automatic and fully-automatic fire.

Abstract: A non-firing housing imitates a functioning receiver for a semi-automatic or fully automatic gun. The non-firing housing includes a thick sidewall that is thicker than the corresponding sidewall of the functioning receiver such that the non-firing housing prohibits the receipt of at least one of the required firing components that are received in the functioning receiver to create a functioning gun, thus prohibiting the use of the non-firing housing as a functioning receiver in a semi-automatic or fully automatic gun.

Abstract: A trigger assembly for a trigger housing for an M240 Assault Rifle is provided having a switch accessible at the outside of the trigger housing for changing the firing of the rifle between semi-automatic and fully-automatic fire.

Abstract: A striking mechanism for the semi-automatic operation of a cartridge firing firearm includes a receiver, a barrel attached to the receiver and providing a breach, an op rod assembly, and a bolt adapted for reciprocating movement within the receiver and engagable with the breach of the barrel and the face of a cartridge chambered therein. The bolt carries a primary firing pin, and a bolt lock means is pivotally connected to the bolt for selectively locking the bolt within the receiver. A bolt link assembly is pivotally connected to the bolt lock means and to the op rod assembly. The bolt link assembly provides a bolt link transfer pin. An op rod transfer pin is carried by the op rod assembly and can engage the bolt link transfer pin.