A rifle includes a magazine well, a barrel, an exo-bolt, and a rear magazine support. The barrel is detachably coupled to the magazine well. The barrel includes a forward barrel portion on an end of the barrel opposite the magazine well. The exo-bolt is configured to travel along an exterior of the barrel. The rear magazine support is coupled to the magazine well and opposite the barrel. The rear magazine support is configured to come forward toward the barrel and be secured in a plurality of distances from the barrel to adjust a length of the magazine well.

An ejector mechanism for a firearm includes an ejector disposed at a forward face of a bolt. The ejector includes a hole designed to provide clearance for the firing pin to pass at least partially through the ejector. The hole may include a counterbore on a rear side of the ejector.

A firearm with a lower receiver and bolt catch. The lower receiver may include a first external wall portion that is on the left side of the firearm and a second external wall portion on the right side of the firearm when a front of the lower receiver is facing forward, the rear of lower receiver is facing rearward, the bottom of the lower receiver is facing downward, and the firearm is in a firing position. The firearm may further include a bolt catch for preventing forward movement of the bolt. The bolt catch may include a first external bolt catch portion that exits the first external wall portion of the receiver on the left side of the firearm and a second external bolt catch portion that exits the second external wall portion of the receiver on the right side of the firearm. The bolt catch may further include an internal bolt catch portion within the lower receiver that connects the first external bolt catch portion and the second external bolt catch portion, wherein at least a first portion of the internal bolt catch portion extends in at least one of a rearward direction towards the rear of the receiver, or a downward direction towards the bottom of the lower receiver.

A firearm with a lower receiver and bolt catch. The lower receiver may include a first external wall portion that is on the left side of the firearm and a second external wall portion on the right side of the firearm when a front of the lower receiver is facing forward, the rear of lower receiver is facing rearward, the bottom of the lower receiver is facing downward, and the firearm is in a firing position. The firearm may further include a bolt catch for preventing forward movement of the bolt. The bolt catch may include a first external bolt catch portion that exits the first external wall portion of the receiver on the left side of the firearm and a second external bolt catch portion that exits the second external wall portion of the receiver on the right side of the firearm. The bolt catch may further include an internal bolt catch portion within the lower receiver that connects the first external bolt catch portion and the second external bolt catch portion, wherein at least a first portion of the internal bolt catch portion extends in at least one of a rearward direction towards the rear of the receiver, or a downward direction towards the bottom of the lower receiver.

Retaining devices securable on firearms are selectively operable to engage and retain a bolt assembly in a substantially-fixed position for an indeterminate period of time. The retaining devices include a mounting plate securable to the receiver and a retention pin that extends through a passage in the mounting plate. The retention pin extends axially between first and second ends that project outwardly beyond the mounting plate. The retention pin is supported on the mounting plate for axial displacement between a first pin position and a second pin position. In the first pin position, the second end of the retention pin engages and retains the bolt assembly in a substantially-fixed position relative to the receiver. In the second pin position, the second end of the retention pin is disengaged from the bolt assembly.

Retaining devices securable on firearms are selectively operable to engage and retain a bolt assembly in a substantially-fixed position for an indeterminate period of time. The retaining devices include a mounting plate securable to the receiver and a retention pin that extends through a passage in the mounting plate. The retention pin extends axially between first and second ends that project outwardly beyond the mounting plate. The retention pin is supported on the mounting plate for axial displacement between a first pin position and a second pin position. In the first pin position, the second end of the retention pin engages and retains the bolt assembly in a substantially-fixed position relative to the receiver. In the second pin position, the second end of the retention pin is disengaged from the bolt assembly.

An improved bolt and bolt carrier with integral gas key having an extension nozzle threadedly secured and pinned to the gas key for use with a direct gas operated firearm is provided. The extension nozzle is designed to receive a portion of the host firearm's gas operating system. The firing pin retaining pin is oriented so as to expose its widest profile to the firing pin's annular flange, increasing its service life. The bolt has a plurality of lugs extending from its forward end. The extractor recess is constructed so that the face of the bolt is round and the adjacent lugs fully supported. The extractor engages approximately 17% more of a seated ammunition cartridge's rim as compared to the prior art AR15/M16 extractor. The result is an improved bolt and bolt carrier which provides for increased operational reliability.

An improved bolt and bolt carrier with integral gas key having an extension nozzle threadedly secured and pinned to the gas key for use with a direct gas operated firearm is provided. The extension nozzle is designed to receive a portion of the host firearm's gas operating system. The firing pin retaining pin is oriented so as to expose its widest profile to the firing pin's annular flange, increasing its service life. The bolt has a plurality of lugs extending from its forward end. The extractor recess is constructed so that the face of the bolt is round and the adjacent lugs fully supported. The extractor engages approximately 17% more of a seated ammunition cartridge's rim as compared to the prior art AR15/M16 extractor. The result is an improved bolt and bolt carrier which provides for increased operational reliability.

An improved bolt and bolt carrier with integral gas key having an extension nozzle threadedly secured and pinned to the gas key for use with a direct gas operated firearm is provided. The extension nozzle is designed to receive a portion of the host firearm's gas operating system. The firing pin retaining pin is oriented so as to expose its widest profile to the firing pin's annular flange, increasing its service life. The bolt has a plurality of lugs extending from its forward end. The extractor recess is constructed so that the face of the bolt is round and the adjacent lugs fully supported. The extractor engages approximately 17% more of a seated ammunition cartridge's rim as compared to the prior art AR15/M16 extractor. The result is an improved bolt and bolt carrier which provides for increased operational reliability.

An improved bolt and bolt carrier with integral gas key having an extension nozzle threadedly secured and pinned to the gas key for use with a direct gas operated firearm is provided. The extension nozzle is designed to receive a portion of the host firearm's gas operating system. The firing pin retaining pin is oriented so as to expose its widest profile to the firing pin's annular flange, increasing its service life. The bolt has a plurality of lugs extending from its forward end. The extractor recess is constructed so that the face of the bolt is round and the adjacent lugs fully supported. The extractor engages approximately 17% more of a seated ammunition cartridge's rim as compared to the prior art AR15/M16 extractor. The result is an improved bolt and bolt carrier which provides for increased operational reliability.