The present disclosure is directed to firearms that can receive and fire bullets from ammunition with different cartridge case sizes. For example, the receiver may fire a bullet from either a short cartridge, a medium cartridge, or long cartridge after the short, medium, or long cartridge is received by a receiver of the firearm. This firearm may include a receiver portion and a bolt portion that lock together at different relative locations when cartridges of different lengths are received by the receiver portion. The receiver portion may include a first type of alignment retention features (e.g. protrusions) and the bolt portion may include a second type of alignment retention features (e.g. recessions). Once a firearm cartridge is located inside of the firearm, it may be fired based on the receiver and the bolt portions being locked together via physical engagement of the different types of alignment retention features.

The present disclosure is directed to firearms that can receive and fire bullets from ammunition with different cartridge case sizes. For example, the receiver may fire a bullet from either a short cartridge, a medium cartridge, or long cartridge after the short, medium, or long cartridge is received by a receiver of the firearm. This firearm may include a receiver portion and a bolt portion that lock together at different relative locations when cartridges of different lengths are received by the receiver portion. The receiver portion may include a first type of alignment retention features (e.g. protrusions) and the bolt portion may include a second type of alignment retention features (e.g. recessions). Once a firearm cartridge is located inside of the firearm, it may be fired based on the receiver and the bolt portions being locked together via physical engagement of the different types of alignment retention features.

System for a multi-caliber self-loading action. Specifically, the system is comprised of a multi-position locking assembly and a self-regulating gas assembly. The multi-position locking assembly is comprised of a bolt carrier, a spring, a bolt, a lock, and a cam assembly. The cam assembly will interface between the bolt carrier and the bolt to rotate the bolt through the bolt carrier. The lock will interface with the bolt, to lock the bolt in at least one locked position based on the caliber of the round inserted. The self-regulating gas assembly directs gas from the gas regulation to at least one piston cup, which will then cause the piston to act on the multi-position locking assembly.

System for a multi-caliber self-loading action. Specifically, the system is comprised of a multi-position locking assembly and a self-regulating gas assembly. The multi-position locking assembly is comprised of a bolt carrier, a spring, a bolt, a lock, and a cam assembly. The cam assembly will interface between the bolt carrier and the bolt to rotate the bolt through the bolt carrier. The lock will interface with the bolt, to lock the bolt in at least one locked position based on the caliber of the round inserted. The self-regulating gas assembly directs gas from the gas regulation to at least one piston cup, which will then cause the piston to act on the multi-position locking assembly.

A rotating bolt firearm may be configured to fire a .308 cartridge. However, the firearm may have a reduced weight in comparison to standard .308 rifles. The firearm may have many components typically used in a .223 rifle. The firearm may include a barrel extension with an extractor gap, which allows a .308 bolt to fit within a .223 sized barrel extension. The firearm may comprise an elongated magazine well in comparison to a .223 mil-spec rifle. The firearm may weigh less than 6.8 pounds with a 16-inch barrel, or less than 6.3 pounds with a 10.5 inch barrel.

A rotating bolt firearm may be configured to fire a .308 cartridge. However, the firearm may have a reduced weight in comparison to standard .308 rifles. The firearm may have many components typically used in a .223 rifle. The firearm may include a barrel extension with an extractor gap, which allows a .308 bolt to fit within a .223 sized barrel extension. The firearm may comprise an elongated magazine well in comparison to a .223 mil-spec rifle. The firearm may weigh less than 6.8 pounds with a 16-inch barrel, or less than 6.3 pounds with a 10.5 inch barrel.

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.

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 secondary firearm with a rail mount attachable to a rail assembly of a primary firearm is disclosed. The secondary firearm comprises a body having at least one retaining pin hole and a bolt stop hole and a housing disposed about the body. The housing comprises at least one retaining pin aperture and/or a bolt stop aperture. The secondary firearm also includes at least one fastener disposed within at least one of the at least one retaining pin aperture and the at least one retaining pin hole and/or the bolt stop aperture and the bolt stop hole to fasten the housing to the body.

A secondary firearm with a rail mount attachable to a rail assembly of a primary firearm is disclosed. The secondary firearm comprises a body having at least one retaining pin hole and a bolt stop hole and a housing disposed about the body. The housing comprises at least one retaining pin aperture and/or a bolt stop aperture. The secondary firearm also includes at least one fastener disposed within at least one of the at least one retaining pin aperture and the at least one retaining pin hole and/or the bolt stop aperture and the bolt stop hole to fasten the housing to the body.