A barrel assembly for use in a semiautomatic firearm, including a barrel and a takedown lever. A rear portion of the barrel includes a follower lug and a rear lug extending from an underside of the rear portion. The follower lug further includes a follower notch. A pin of the takedown lever includes a notch with a vertical face configured to contact a vertical face of the follower notch when the firearm is in the locked position. The rear lug is configured to be supported by a portion of a locking block of the firearm prior to firing and during a portion of the recoil period. The modifications to the barrel assembly result in increased dwell time and accuracy of the firearm.

An automatic firearm breech mechanism is provided that ensures that the delaying roller remains an integral part of the breech mechanism after removing the breech mechanism from the firearm. The automatic firearm breech mechanism may include a breech, a breech carrier, and a delaying roller that is positioned between a rear vertical wall of the breech and a front vertical wall of the breech carrier. The delaying roller may move vertically while between the rear vertical wall of the breech and the front vertical wall of the breech carrier. A modified cage may surround the working area of the delaying roller. The cage may be a strip bent into the shape of an inverted letter U, featuring an opening located on its horizontal wall, while its vertical walls are fitted with a slide stop at both ends.

A rifle platform with semi-automatic, select fire, and/or fully automatic shooting options uses a pistol cartridge. The rifle barrel includes an extension having a ramp for loading the cartridges and having a key way for the shell extractor. The magazine of the rifle is mounted to the lower receiver so as to load the cartridges in a direction perpendicular to the rifle barrel. The magazine follower automatically locks the bolt after the last cartridge is fired. The bolt and bolt carrier are integrally machined, and fully enclose the cartridge to preclude out of battery firing.

A rifle platform with semi-automatic, select fire, and/or fully automatic shooting options uses a pistol cartridge. The rifle barrel includes an extension having a ramp for loading the cartridges and having a key way for the shell extractor. The magazine of the rifle is mounted to the lower receiver so as to load the cartridges in a direction perpendicular to the rifle barrel. The magazine follower automatically locks the bolt after the last cartridge is fired. The bolt and bolt carrier are integrally machined, and fully enclose the cartridge to preclude out of battery firing.

A suppressed pistol has a breech block and a slide mounted on a frame. The breech block and slide are separate pieces, movable relatively to one another and the frame. A link extends between the breech block and the frame. The link carries a cam and a cam follower. The cam follower on the link engages a cam on the frame, the cam on the link engages a cam follower on the slide. Action between the cams, cam followers and the link causes separation between the breech block and the slide during operation of the pistol. The suppressor includes a container having baffle plates with truncated cones defining openings offset from the geometric centers of the baffle plates.

A suppressed pistol has a breech block and a slide mounted on a frame. The breech block and slide are separate pieces, movable relatively to one another and the frame. A link extends between the breech block and the frame. The link carries a cam and a cam follower. The cam follower on the link engages a cam on the frame, the cam on the link engages a cam follower on the slide. Action between the cams, cam followers and the link causes separation between the breech block and the slide during operation of the pistol. The suppressor includes a container having baffle plates with truncated cones defining openings offset from the geometric centers of the baffle plates.

A spring system for blowback action is provided with a control piece (2) and pusher piece (3) supported so that it can be displaced on the guide rod (7). On its end, a buffer (4) is arranged with a buffer spring (6). The guide rod (7) is also used for guiding the closing spring (8). Between the control piece (2) and pusher piece (3) there are five rollers (10) in a recess (9) of the guide rod (7), and these rollers cause a delay of the action during the blowback after the discharge of a shot.

A system for firing reduced energy cartridges from a modern sporting rifle utilizes a bolt assembly weighing less than a conventional bolt assembly for such rifles and utilizes blow back for cycling the bolt assembly rather than gas operation. A bolt insert in a polymer bolt carrier of the bolt assembly has a projection that fits within a recess on the rear face of reduced energy cartridges. The reduced energy cartridges having a polymer casing, a rimfire power load for propellant, the power load recessed from the rear face of the casing. Tuning the bolt may comprise adjusting the weight of the bolt or the sliding resistance of the bolt assembly in the upper receiver. The bolt may be formed by metal injection molding with a polymer bolt carrier attached thereto.

A system for firing reduced energy cartridges from a modern sporting rifle utilizes a bolt assembly weighing less than a conventional bolt assembly for such rifles and utilizes blow back for cycling the bolt assembly rather than gas operation. A bolt insert in a polymer bolt carrier of the bolt assembly has a projection that fits within a recess on the rear face of reduced energy cartridges. The reduced energy cartridges having a polymer casing, a rimfire power load for propellant, the power load recessed from the rear face of the casing. Tuning the bolt may comprise adjusting the weight of the bolt or the sliding resistance of the bolt assembly in the upper receiver. The bolt may be formed by metal injection molding with a polymer bolt carrier attached thereto.

The purpose of the invention is to ensure that the delaying roller remains an integral part of the breech mechanism after removing the breech mechanism from the fire arm. The automatic firearm breech mechanism featuring a breech (3), a breech carrier (4) and a delaying roller (2) that is positioned between the rear vertical wall (32) of the breech (3) and the front vertical wall (41) of the breech carrier (4), moving vertically, while between the rear vertical wall (32) of the breech (3) and the front vertical wall (41) of the breech carrier (4) a modified cage (8) surrounding the delaying roller's (2) working area is placed. The cage (8) created from a strip bent into the shape of the reversed letter U, featuring an opening (82) located on its horizontal wall (81), while its vertical walls (83) are fitted with a slide stop (84) at both ends.