Abstract: A receiver system comprises upper and lower receiver bodies, a lower receiver body, a bolt carrier, and an action-control lever. The upper receiver body is a semi-automatic firearm upper receiver body. The lower receiver body includes a stock mounting flange having a stock receptacle that is matingly engageable with a receiver engaging portion of a stock. The bolt carrier is slidably disposed within a bolt carrier receiving bore of the upper receiver body. The action-control lever has a hand loop and a first attachment arm having a proximate end portion thereof attached to the hand loop. The first attachment arm is pivotably attached at a distal end thereof to the lower receiver body for being pivoted between a battery-ready position and a cartridge-ejecting position relative to the lower receiver body. The action-control lever is attached to the bolt carrier through an articulating coupling assembly.

Abstract: A firearm as disclosures herein comprises a main receiver body, a barrel, a breech bolt structure, a buffer assembly, a trigger group assembly, a bolt catch and at least one of an auto-sear, a magazine adapter and a breech bolt anti-rotation structure. The main receiver body is preferably of a monolithic construction whereby the handguard and breech bolt carrying bore can be manufactured from a single piece of material. The auto-sear is tripped by engagement with a buffer of the buffer assembly. The magazine adapter has an exterior surface structure engaged with a mating interior surface structure of a magazine well space of the main receiver body. A distal end portion of the breech bolt anti-rotation structure is engageable by the buffer for limiting forward travel of the buffer when the barrel is detached from the main receiver body.

Abstract: A firearm as disclosures herein comprises a main receiver body, a barrel, a breech bolt structure, a buffer assembly, a trigger group assembly, a bolt catch and at least one of an auto-sear, a magazine adapter and a breech bolt anti-rotation structure. The main receiver body is preferably of a monolithic construction whereby the handguard and breech bolt carrying bore can be manufactured from a single piece of material. The auto-sear is tripped by engagement with a buffer of the buffer assembly. The magazine adapter has an exterior surface structure engaged with a mating interior surface structure of a magazine well space of the main receiver body. A distal end portion of the breech bolt anti-rotation structure is engageable by the buffer for limiting forward travel of the buffer when the barrel is detached from the main receiver body.

Abstract: A firearm as disclosures herein comprises a main receiver body, a barrel, a breech bolt structure, a buffer assembly, a trigger group assembly, a bolt catch and at least one of an auto-sear, a magazine adapter and a breech bolt anti-rotation structure. The main receiver body is preferably of a monolithic construction whereby the handguard and breech bolt carrying bore can be manufactured from a single piece of material. The auto-sear is tripped by engagement with a buffer of the buffer assembly. The magazine adapter has an exterior surface structure engaged with a mating interior surface structure of a magazine well space of the main receiver body. A distal end portion of the breech bolt anti-rotation structure is engageable by the buffer for limiting forward travel of the buffer when the barrel is detached from the main receiver body.

Abstract: A firearm as disclosures herein comprises a main receiver body, a barrel, a breech bolt structure, a buffer assembly, a trigger group assembly, a bolt catch and at least one of an auto-sear, a magazine adapter and a breech bolt anti-rotation structure. The main receiver body is preferably of a monolithic construction whereby the handguard and breech bolt carrying bore can be manufactured from a single piece of material. The auto-sear is tripped by engagement with a buffer of the buffer assembly. The magazine adapter has an exterior surface structure engaged with a mating interior surface structure of a magazine well space of the main receiver body. A distal end portion of the breech bolt anti-rotation structure is engageable by the buffer for limiting forward travel of the buffer when the barrel is detached from the main receiver body.

Abstract: A firearm preferably permits a user to readily change ammunition type and associated magazine configuration at user discretion. Such a firearm may be optimally practiced as a pistol, rifle, or submachine gun but is not limited to a particular caliber size or configurations. A main receiver body of the firearm is preferably of a monolithic construction whereby the handguard and breech bolt carrying bore can be manufactured from a single piece of material such as, for example, an aluminum extrusion or polymer injection molded component. In at least one or more of these respects, the firearm is of an improved design to both simplify and speed manufacturing and assembly, while simultaneously reducing manufacturing costs normally associated with the firearm industry's usual state-of-the-art (e.g., prior art) methods.

Abstract: A rifle kit comprises a rifle receiver structure having a central passage configured for having a substantially as-manufactured breech bolt of a pistol mounted therein and has one or more shoulder stock mounting portions configured for having a shoulder stock structure engaged therewith. A substantially as-manufactured breech bolt of the kit is configured by an original equipment manufacturer (OEM) thereof for being mounted on a pistol receiver body configured by the OEM. The rifle barrel is mountable within the central passage of the rifle receiver structure. A chamber end portion of the rifle barrel is configured for engaging a mating portion of the substantially as-manufactured breech bolt. A shoulder stock structure of the kit includes a receiver structure engaging portion configured for allowing the shoulder stock structure to be mounted on the rifle receiver structure exclusively through engagement with the one or more stock mounting portions of the rifle receiver structure.

Abstract: A rifle includes an upper receiver body, a lower receiver body detachably attached to the upper receiver body, a stock and a bolt carrier group. The upper receiver body has a bolt carrier receiving bore exposed at a stock engaging portion thereof. The stock includes a recoil spring receiving bore therein exposed at a mounting portion thereof. The mounting portion of the stock is engaged with the stock engaging portion of the lower receiver body in a manner whereby the recoil spring receiving bore is accessible from the bolt carrier receiving bore. A centerline axis of the recoil spring receiving bore is skewed with respect to a centerline axis of the bolt carrier receiving bore. The bolt carrier group has a bolt carrying structure slideably disposed within the bolt carrier receiving bore, a recoil spring engaging structure slideably disposed within the recoil spring receiving bore and a linkage member structure pivotably engaged between the bolt carrying structure and the recoil spring engaging structure.

Abstract: A rifle includes an upper receiver body, a lower receiver body detachably attached to the upper receiver body, a stock and a bolt carrier group. The upper receiver body has a bolt carrier receiving bore exposed at a stock engaging portion thereof. The stock includes a recoil spring receiving bore therein exposed at a mounting portion thereof. The mounting portion of the stock is engaged with the stock engaging portion of the lower receiver body in a manner whereby the recoil spring receiving bore is accessible from the bolt carrier receiving bore. A centerline axis of the recoil spring receiving bore is skewed with respect to a centerline axis of the bolt carrier receiving bore. The bolt carrier group has a bolt carrying structure slideably disposed within the bolt carrier receiving bore, a recoil spring engaging structure slideably disposed within the recoil spring receiving bore and a linkage member structure pivotably engaged between the bolt carrying structure and the recoil spring engaging structure.

Abstract: A kit for modifying a bolt carrier group actuating apparatus of a firearm configured by its original manufacturer to have a gas-driven bolt carrier has a gas expansion assembly and an operating rod. The gas expansion assembly is configured for receiving combustion gases from an as-manufactured OEM gas block of a firearm and for facilitating expansion of the gases for generating a bolt carrier driving force. The operating rod is engagable between the gas expansion assembly and an operating rod engaging lug of a bolt carrier. The operating rod is configured to mechanically transmit the bolt carrier driving force to the operating rod engaging lug.

Abstract: A kit for modifying a bolt carrier group actuating apparatus of a firearm configured by its original manufacturer to have a gas-driven bolt carrier has a gas expansion assembly and an operating rod. The gas expansion assembly is configured for receiving combustion gases from an as-manufactured OEM gas block of a firearm and for facilitating expansion of the gases for generating a bolt carrier driving force. The operating rod is engagable between the gas expansion assembly and an operating rod engaging lug of a bolt carrier. The operating rod is configured to mechanically transmit the bolt carrier driving force to the operating rod engaging lug.

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 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 kit for providing a handgrip on a firearm includes a handgrip body mountable on a handgrip body mounting structure of the firearm. The handgrip body includes an ammunition storage space therein. The ammunition storage space defines a storage space opening in a surface of the handgrip body through which a round of ammunition can be inserted into the ammunition storage space. A storage space cover has a primer recess within an ammunition support surface thereof and is attached to the handgrip body in a manner allowing the storage space cover to be moved between an open position in which access to the storage space opening is provided and a closed position in which the ammunition support surface extends over the storage space opening. A portion of the primer recess overlies a primer occupying region of the ammunition storage space when the storage space cover is in the closed position.

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 receiver assembly for a firearm has an as-manufactured original equipment manufacturer (OEM) receiver body, an operating rod bushing, and an operating rod. The as-manufactured OEM receiver body has therein a bolt carrier bore and a gas tube lug receiving portion. The gas tube lug receiving portion intersects the bolt carrier bore. A gas lug bore extends through the receiver body between the gas tube lug receiving portion of the receiver body and a front face of the receiver body. The operating rod bushing is mounted within the gas lug bore of the as-manufactured OEM receiver body. The operating rod extends through a central passage of the operating rod bushing into the gas tube lug receiving portion of the as-manufactured OEM receiver body. The central passage of the operating rod bushing and the operating rod are jointly configured for limiting radial displacement of the operating rod with respect to the operating rod bushing.

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 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 rifle kit comprises a rifle receiver structure having a central passage configured for having a substantially as-manufactured breech bolt of a pistol mounted therein and has one or more shoulder stock mounting portions configured for having a shoulder stock structure engaged therewith. A substantially as-manufactured breech bolt of the kit is configured by an original equipment manufacturer (OEM) thereof for being mounted on a pistol receiver body configured by the OEM. The rifle barrel is mountable within the central passage of the rifle receiver structure. A chamber end portion of the rifle barrel is configured for engaging a mating portion of the substantially as-manufactured breech bolt. A shoulder stock structure of the kit includes a receiver structure engaging portion configured for allowing the shoulder stock structure to be mounted on the rifle receiver structure exclusively through engagement with the one or more stock mounting portions of the rifle receiver structure.

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.