Abstract: A kit for modifying a bolt carrier group actuating apparatus of a firearm manufacturer-configured with a gas-driven bolt carrier comprises a gas expansion assembly, an operating rod driven bolt carrier and an operating rod. The gas expansion assembly is configured for receiving combustion gases from an as-manufactured OEM gas block of the firearm and for facilitating expansion of said gases for generating a bolt carrier driving force. The operating rod driven bolt carrier includes an operating rod engaging lug. The operating rod driven bolt carrier is configured for being operably engaged within an as-manufactured OEM receiver body of the firearm with the operating rod engaging lug located in a gas tube lug receiving portion of the as-manufactured OEM receiver body. The operating rod is engagable between the gas expansion assembly and the operating rod engaging lug.

Abstract: A firearm comprises an upper receiver body and a lower receiver assembly. The upper receiver body is configured for receiving belt-fed ammunition and the lower receiver assembly is attached to the upper receiver body. The lower receiver assembly includes a receiver body having an accessory mounting structure, a trigger group mounting structure, one of an integrally-formed, non-detachable butt-stock mounting structure and an integrally-formed, non-detachable butt-stock, and one of a hand grip mounting structure and an integrally-formed, non-detachable hand grip.

Abstract: A firearm comprises an upper receiver body and a lower receiver assembly. The upper receiver body is configured for receiving belt-fed ammunition and the lower receiver assembly is attached to the upper receiver body. The lower receiver assembly includes a receiver body having an accessory mounting structure, a trigger group mounting structure, one of an integrally-formed, non-detachable butt-stock mounting structure and an integrally-formed, non-detachable butt-stock, and one of a hand grip mounting structure and an integrally-formed, non-detachable hand grip.

Abstract: A firearm receiver system including a receiver body, an ammunition belt feeding assembly and a bolt carrier. The receiver body includes a first face and a second face approximately opposite the first face. The receiver body is configured for having means for triggering engaged therewith at the first face and for receiving belt-fed ammunition through the second face. The ammunition belt feeding assembly is mounted at least partially on the receiver body and the ammunition belt feeding assembly is configured for supplying the belt-fed ammunition to the receiver body through the second face. The bolt carrier is movably mounted on the receiver body between the first and second faces of the receiver body and the bolt carrier is configured for being actuated by gas-energized piston-driven means.

Abstract: A firearm receiver system including a receiver body, an ammunition belt feeding assembly and a bolt carrier. The receiver body includes a first face and a second face approximately opposite the first face. The receiver body is configured for having means for triggering engaged therewith at the first face and for receiving belt-fed ammunition through the second face. The ammunition belt feeding assembly is mounted at least partially on the receiver body and the ammunition belt feeding assembly is configured for supplying the belt-fed ammunition to the receiver body through the second face. The bolt carrier is movably mounted on the receiver body between the first and second faces of the receiver body and the bolt carrier is configured for being actuated by gas-energized piston-driven means.

Abstract: A bolt catch assembly including a bolt engagement leg, a sliding member engagement leg, a contact member and an arrangement for enabling the bolt catch assembly to pivot about a pivot axis. The bolt engagement leg is configured for engaging a bolt of a firearm to hold the bolt in an open position. The sliding member engagement leg is connected to the bolt engagement leg. The contact member resiliently mounted on the sliding member engagement leg. The contact member is configured for being displaced between a static position and a displaced position whereby a catch engagement force is generated in response to the contact member being moved from the static position toward the displaced position. The arrangement for enabling the bolt catch assembly to pivot is disposed between the bolt engagement leg and the sliding member engagement leg thereby enabling the bolt engagement leg and the sliding member engagement leg to be pivoted in unison about the pivot axis of the bolt catch assembly.

Abstract: A bolt catch assembly including a bolt engagement leg, a sliding member engagement leg, a contact member and an arrangement for enabling the bolt catch assembly to pivot about a pivot axis. The bolt engagement leg is configured for engaging a bolt of a firearm to hold the bolt in an open position. The sliding member engagement leg is connected to the bolt engagement leg. The contact member resiliently mounted on the sliding member engagement leg. The contact member is configured for being displaced between a static position and a displaced position whereby a catch engagement force is generated in response to the contact member being moved from the static position toward the displaced position. The arrangement for enabling the bolt catch assembly to pivot is disposed between the bolt engagement leg and the sliding member engagement leg thereby enabling the bolt engagement leg and the sliding member engagement leg to be pivoted in unison about the pivot axis of the bolt catch assembly.

Abstract: An apparatus adapted for actuating a bolt carrier group apparatus comprising a piston tube attached to a receiver assembly. An operating rod is disposed in a bore of the piston tube. A piston is engaged with a first end of the operating rod. The operating rod moves from a static position to a displaced position when a combustion gas is exposed to a face of the piston. A bolt carrier including a bolt carrier lug is disposed in a bolt carrier lug channel of an upper receiver body. A tappet rod is engaged with the bolt carrier lug. The tappet rod moves substantially in unison with the operating rod. A yoke is attached to the tappet rod and to the operating rod. The yoke is mounted movably on the piston tube. An adjustable pressure regulator is coupled to the piston tube for regulating discharge of the combustion gas therethrough.

Abstract: A method of reconfiguring a firearm receiver system comprises the operations of providing a substantially as-manufactured OEM lower receiver assembly capable of having an ammunition magazine attached thereto for communicating ammunition to an OEM upper receiver assembly capable of having ammunition communicated thereto exclusively from the OEM lower receiver assembly; mounting a supplemental upper receiver assembly capable of having belt-fed ammunition communicated thereto on the OEM lower receiver assembly; mounting an ammunition belt feeding assembly on the supplemental upper receiver assembly; attaching a piston tube assembly to the supplemental upper receiver assembly; coupling a tappet assembly to the piston tube assembly; engaging the tappet assembly with a bolt carrier of the supplemental upper receiver assembly; and attaching an adjustable pressure regulator to the piston tube assembly.

Abstract: An embodiment of a method of reconfiguring a firearm receiver system for receiving ammunition from a magazine and from an ammunition belt is disclosed herein.

Abstract: An embodiment of an apparatus adapted for actuating a bolt carrier group of a receiver assembly is disclosed herein. The embodiment of such an apparatus comprises a piston tube attached to a receiver assembly. An operating rod is disposed in a bore of the piston tube. A piston is engaged with a first end of the operating rod. The operating rod moves from a static position to a displaced position when a combustion gas is exposed to a face of the piston. A bolt carrier including a bolt carrier lug is disposed in a bolt carrier lug channel of an upper receiver body. A tappet rod is engaged with the bolt carrier lug. The tappet rod moves substantially in unison with the operating rod. A yoke is attached to the tappet rod and to the operating rod. The yoke is mounted movably on the piston tube. An adjustable pressure regulator is coupled to the piston tube for regulating discharge of the combustion gas therethrough.