A lightweight machine gun receiver has a frame having opposed left and right shell portions configured to separably connect to each other in a connected condition, when in the connected condition, the frame defining an internal space configured to receive a reciprocating bolt, have a barrel connection facility, and have a trigger connection facility, when in the connected condition, the frame being an elongated body having a left side panel having upper and lower edges and an opposed right side panel having upper and lower edges, each of the left and right shell portions having top and bottom spans extending laterally from the associated side panel toward corresponding opposed top and bottom spans, the top and bottom spans having respective free ends having respective top and bottom span mating facilities configured to mate with each other, and the top and bottom span mating facilities each having a sliding interface.

There is a multi-caliber weapon system. The multi-caliber weapon system comprises: a frame body, with a front body portion, a middle body portion, and a rear body portion, and including: a plurality of frame flanges, each frame flange being coupled to an interior of the frame body and extending upwardly therefrom; a barrel, removably coupled to the front body portion of the frame body, including: a plurality of barrel rings, each barrel ring being disposed around a circumference of the barrel and spaced along a length of the barrel, wherein the barrel rings are disposed on the frame flanges; a chamber, removably coupled to the middle body portion of the frame body, and removably coupled to the barrel; and a bolt, removably coupled to rear body portion of the frame body, removably coupled to the chamber, and including: a bolt face, removably coupled to a front bolt portion.

A link feed assembly. There is: a bolt carrier near a chamber of a modular weapon system; an infeed ramp, coupled to a first side of a weapon frame near the chamber; an outfeed ramp, coupled to a second side of the capon frame near the chamber and opposite the infeed ramp, positioned to form a space between the infeed ramp and the outfeed ramp; and a feed arm assembly coupled to the weapon frame and extending over the space between the infeed ramp and the outfeed ramp, the feed arm assembly functionally coupled to the bolt carrier such that cycling of the bolt carrier forward and backwards causes cycling of the feed arm assembly in a circuitous motion, the feed arm including a grabbing protrusion that is shaped to grab a top portion of a link during cycling of the feed arm assembly.

A barrel mounting system to mount a barrel to a barrel mount of a firearm body includes a mount receiver secured to the barrel mount. The mount receiver includes axial channels and receiver threads disposed on an interior surface. The system further includes a barrel sleeve disposed around the barrel proximal to the proximal end of the barrel. The barrel sleeve includes sleeve threads disposed near a proximal end on an exterior surface and sized to slide through the axial channels and, when rotated, to engage the receiver threads. The system further includes a barrel collar disposed around the barrel and secured to the barrel and to limit the axial position of the barrel sleeve.

There is a multi-caliber weapon system. The multi-caliber weapon system comprises: a frame body, with a front body portion, a middle body portion, and a rear body portion, and including: a plurality of frame flanges, each frame flange being coupled to an interior of the frame body and extending upwardly therefrom; a barrel, removably coupled to the front body portion of the frame body, including: a plurality of barrel rings, each barrel ring being disposed around a circumference of the barrel and spaced along a length of the barrel, wherein the barrel rings are disposed on the frame flanges; a chamber, removably coupled to the middle body portion of the frame body, and removably coupled to the barrel; and a bolt, removably coupled to rear body portion of the frame body, removably coupled to the chamber, and including: a bolt face, removably coupled to a front bolt portion.

A barrel extension usable with a firearm and a firearm having a barrel extension is disclosed. The barrel extension may include a barrel extension body extending along a barrel extension central axis between a barrel interface end. The barrel interface end may be configured to be connected to a barrel and the bolt receiving end may be configured to selectively receive a rotatable bolt of the firearm. The barrel extension may further include a plurality of barrel extension lugs at the bolt receiving end having bolt lug receiving openings therebetween, wherein each of the plurality of barrel extension lugs has a lug inner surface that is a first distance from the central axis, and each of the plurality of receiving openings have a receiving opening inner surface that is a second distance from the central axis. The barrel extension further includes a first feed ramp with a first feed ramp surface configured to guide a firearm cartridge, a second feed ramp with a second feed ramp surface configured to guide a firearm cartridge, and a ramp divider between the first feed ramp and the second feed ramp, wherein the ramp divider has a ramp divider inner surface that is a third distance from the central axis.

Adapters for mounting an accessory on a firearm, firearm accessories configured to mount to those adapters, and sheath or handguard assemblies of firearms are disclosed. The recited accessory adapter is substantially annular or tubular in shape, and includes at least two portions that are arranged adjacently along the barrel axis of the firearm. A rear portion is formed on the weapon side of the adapter, so that the rear portion is geometrically complementary to the front end of a firearm sheath, at least in part, and a front portion of the adapter includes a cylindrical coupling surface on the outside for coupling of the accessory, where the coupling surface includes at least one bayonet extension that projects radially outwards.

A lightweight machine gun receiver has a frame having opposed left and right shell portions configured to separably connect to each other in a connected condition, when in the connected condition, the frame defining an internal space configured to receive a reciprocating bolt, have a barrel connection facility, and have a trigger connection facility, when in the connected condition, the frame being an elongated body having a left side panel having upper and lower edges and an opposed right side panel having upper and lower edges, each of the left and right shell portions having top and bottom spans extending laterally from the associated side panel toward corresponding opposed top and bottom spans, the top and bottom spans having respective free ends having respective top and bottom span mating facilities configured to mate with each other, and the top and bottom span mating facilities each having a sliding interface.

A barrel mounting system to mount a barrel to a barrel mount of a firearm body includes a mount receiver secured to the barrel mount. The mount receiver includes axial channels and receiver threads disposed on an interior surface. The system further includes a barrel sleeve disposed around the barrel proximal to the proximal end of the barrel. The barrel sleeve includes sleeve threads disposed near a proximal end on an exterior surface and sized to slide through the axial channels and, when rotated, to engage the receiver threads. The system further includes a barrel collar disposed around the barrel and secured to the barrel and to limit the axial position of the barrel sleeve.

Firearms, particularly rifles, including an upper housing having a barrel, where the barrel and the upper housing are interconnected by means of a guide. In order to improve the connection, the guide includes corresponding prismatic guide surfaces that extend in parallel with the barrel shaft when the firearm is mounted and ready to fire, and the barrel is secured to the upper housing by a tensioning element that can rotate in the upper housing about an axis of rotation that extends normally with respect to the firearm center plane, and the tensioning element includes a tensioning portion and an actuating portion.