The modular upper receiver assembly for firearms is an adapter allowing interchanging of barrels of different calibers to attach to an upper receiver assembly. The adapter assembly serves to provide a quick changeover coupling means for connecting an assortment of barrels of different calibers and lengths to the receiver. The coupling includes a barrel retaining bushing and adapter pair with threaded surfaces on the receiver for a threaded engagement, reinforced with threaded fastener compression for improved rigidity.

A mechanism for extraction caseless ammunition, the mechanism for extraction including a receiver (84) interacting with the lid of the receiver (85); lock frame (86) which interacts with the lid of the receiver; bolt (88) made in the lock frame; a conical bushing (93) installed inside the bolt through the firing pin (89); an extractor (95), wherein lock frame is made with a front ledge (87); on the front end of the firing pin the conical part (90) is made; conical bushing (93) is made with interior ledges (94); a shaft (103) with a circular groove (104); the rear part (102) passes into the lower ledge (106) which has a front inclined area (107) and a rear horizontal area (108) and the lower ledge (106) passes into the upper ledge (109) which has a front inclined area (110), an upper horizontal area (111) and a rear inclined area (112).

A mechanism for extraction caseless ammunition, the mechanism for extraction including a receiver (84) interacting with the lid of the receiver (85); lock frame (86) which interacts with the lid of the receiver; bolt (88) made in the lock frame; a conical bushing (93) installed inside the bolt through the firing pin (89); an extractor (95), wherein lock frame is made with a front ledge (87); on the front end of the firing pin the conical part (90) is made; conical bushing (93) is made with interior ledges (94); a shaft (103) with a circular groove (104); the rear part (102) passes into the lower ledge (106) which has a front inclined area (107) and a rear horizontal area (108) and the lower ledge (106) passes into the upper ledge (109) which has a front inclined area (110), an upper horizontal area (111) and a rear inclined area (112).

A magazine conversion system mounts within a magazine well of a lower receiver, and includes a front spacer having a wedge-shaped main body with a lower end, and an upper end having a feed ramp extending upwardly therefrom; and a rear spacer having a wedge-shaped main portion with a lower portion and an upper portion having an ejector element extending upwardly therefrom. With the front and rear spacers positioned within the magazine well, at least a portion of the feed ramp and at least part of the ejector element are positioned above the magazine well.

A lower receiver that may be right hand or left hand configurable is provided. The lower receiver includes a static ejector that can be easily configured for right hand or left hand positions within the same lower receiver and a magazine button assembly having a left magazine button and a right magazine button that are operatively coupled together so that either magazine button can be pushed to release the magazine. This allows the gun builder to use this one lower receiver to build a right or left handed rifle.

A lower receiver that may be right hand or left hand configurable is provided. The lower receiver includes a static ejector that can be easily configured for right hand or left hand positions within the same lower receiver and a magazine button assembly having a left magazine button and a right magazine button that are operatively coupled together so that either magazine button can be pushed to release the magazine. This allows the gun builder to use this one lower receiver to build a right or left handed rifle.

Firearm ejectors and receivers and firearms including such firearm ejectors are disclosed. An example ejector for a firearm includes a body including a projection extending therefrom, the ejector to be movably coupled to a receiver of the firearm to enable the projection including an engagement surface to be disposed in a movement path of a breechblock, the engagement surface to be engaged by a cartridge casing during a recoil process to enable the cartridge casing to be ejected from the firearm; and a spring to bias the body relative to the receiver, the body to be movably relative to a longitudinal axis of the receiver upon impact with the cartridge.

Firearm ejectors and receivers and firearms including such firearm ejectors are disclosed. An example ejector for a firearm includes a body including a projection extending therefrom, the ejector to be movably coupled to a receiver of the firearm to enable the projection including an engagement surface to be disposed in a movement path of a breechblock, the engagement surface to be engaged by a cartridge casing during a recoil process to enable the cartridge casing to be ejected from the firearm; and a spring to bias the body relative to the receiver, the body to be movably relative to a longitudinal axis of the receiver upon impact with the cartridge.

An improved ejector for a firearm comprising a first contact surface that applies a force on a case of a round of ammunition, and a second contact surface or shelf that applies a force in a direction different than the force applied by the first contact surface to delay the ejection of the case, thus increasing the force couple imparted by first contact surface and an extractor of the firearm, resulting in reliable energy transfer from the bolt assembly of the firearm to the case and improved firearm reliability.

An improved ejector for a firearm comprising a first contact surface that applies a force on a case of a round of ammunition, and a second contact surface or shelf that applies a force in a direction different than the force applied by the first contact surface to delay the ejection of the case, thus increasing the force couple imparted by first contact surface and an extractor of the firearm, resulting in reliable energy transfer from the bolt assembly of the firearm to the case and improved firearm reliability.