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 firearm having a threaded barrel-receiver connection, with a threaded receiver opening for cooperative engagement with a threaded barrel. The receiver is also compatible with a clamping system for engagement of an unthreaded barrel, so that threaded and unthreaded barrels may be used interchangeably. The threads of the receiver may have a flat crested thread profile for sliding engagement upon installation of an unthreaded barrel.

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 firearm stock with barrel-centering feature has an elongated body defining an elongated receiver channel and an elongated barrel channel, the receiver channel defined in part by a flat floor surface facing in upward direction, the receiver channel defined in part by opposed sidewalls extending above the floor surface, a fastener facility at the rear of the receiver channel operable to connect to the tang of the receiver, and a lateral adjustment facility forward of the fastener facility and operable to secure the receiver in a selected lateral angle of pivot about the fastener facility, such that the barrel is centerable within the barrel channel to avoid the barrel touching the stock. The lateral adjustment facility may include a set screw having an axis parallel to the floor surface of the stock. A pair of set screws opposing each other may secure the action in a selected lateral position.

A handguard assembly for a firearm includes a handguard with an internal clamping area. A single-piece index block includes a securing portion for connecting to the handguard and an indexing extension for engaging an indexing feature on the upper receiver of the firearm. The handguard includes internal ribs that provide discrete clamping surfaces for engaging a barrel nut of the firearm. Connecting the index block to the handguard generates a continuous clamping action in the handguard which acts through the ribs to apply a radially-directed circumferentially-applied clamping force on a barrel nut through the discrete clamping surfaces. The indexing feature of the index block engages an indexing feature of the upper receiver to ensure proper alignment of the handguard and the upper receiver.

In one aspect the invention provides a firearm assembly comprising a barrel, receiver and stock, wherein the assembly comprises a first fastener operable to fasten a first section of the receiver so as to locate the receiver in the stock and so as to align the receiver with the stock, wherein the assembly further comprises a second fastener operable to fix a second section of the receiver in place relative to the stock and wherein the second fastener is adjustable to fix the second section of the receiver in place without applying stress to the receiver. Embodiments of this invention may allow fixing a second section in place relative to the stock which place the second section of the receiver assumes naturally when the first part of the receiver is located and aligned by the first fastener.

A non-tilting outer barrel for a toy gun may include a first housing configured to accommodate at least a portion of an inner barrel through which a bullet is discharged, a second housing configured to accommodate at least a portion of a chamber coupled to one end of the inner barrel, a plurality of fixing members disposed in a bore of the first housing thereby restricting vertical movement of the first housing in relation to the inner barrel.

A non-tilting outer barrel for a toy gun may include a first housing configured to accommodate at least a portion of an inner barrel through which a bullet is discharged, a second housing configured to accommodate at least a portion of a chamber coupled to one end of the inner barrel, a plurality of fixing members disposed in a bore of the first housing thereby restricting vertical movement of the first housing in relation to the inner barrel.

An automatic rifle (10) includes a receiver (12), a bolt assembly (110), a trigger mechanism (106), a buttstock assembly (100), a barrel assembly (104), and a grip assembly (102). The receiver (12) is characterized by being a unitary body that houses the bolt assembly (110) and the trigger mechanism (106), and the receiver (12) is configured for the connection thereto of the buttstock assembly (100), the barrel assembly (104), and the grip assembly (102).

A firearm includes a receiver body is provided herein having a plurality of barrel-tightening portions with at least one relief recess therebetween and relief recesses defined in the body on either proximal end. The relief recesses and barrel-tightening portions are sized to allow the barrel-tightening portions to be tightened and loosened independently of each other. A barrel assembly is removably coupled to the receiver body.