Abstract: A bolt assembly that includes a bolt defining at least one bolt opening and an extractor that is configured to pivot relative to the bolt. The extractor may define at least one extractor opening. The bolt assembly may include a pin positioned within the at least one bolt opening and the at least one extractor opening. The bolt assembly may include a retainer that is positioned inward relative to an exterior surface of the bolt assembly. The retainer may be removably coupled to the pin.

Abstract: A cam race comprising a hardened material (harder than a material of an upper receiver) is provided to increase durability of a firearm. The cam race is fit within a groove within an interior sidewall of an upper receiver of the firearm. The cam race comprises a body that is fit within the groove, and a plurality of fastener pins extending away from a rear face of the body that fit within corresponding through-holes of the upper receiver. Distal ends of each of the fastener pins are deformed to form a riveted connection between the cam race and the upper receiver. The cam race defines a slide face along which a cam pin of the firearm slides during a firing process, thereby increasing the durability of the firearm against undesired formation of defects within the interior sidewall of the upper receiver.

Abstract: A stock for a firearm includes a mount, a first member, and a second member. The mount is configured to be coupled to a main body of the firearm. The first member is configured to move along a longitudinal axis defined by the firearm relative to the mount. The second member is configured to move along the longitudinal axis relative to the first member.