Abstract: Systems and methods for firearm receivers are described. Systems may include a receiver body, a tail; and a connection for coupling the receiver body to the tail. The receiver body and the tail may be made from different materials. A receiver system coupling apparatus may include one or more protrusions on a receiver body; and one or more one or more protrusions on a tail. The one or more protrusions on the receiver body may be coupled to the one or more protrusions on the tail to secure the receiver body to the tail. A method for producing a multiple component receiver system may include creating a receiver body from a first material; creating a tail from a second material; and coupling the receiver body to the tail with a connection.

Abstract: A bolt for a firearm is described that can be used to chamber, extract, and/or eject different cartridges that have different outside rim diameters. In one embodiment, the bolt includes a bolt head that is configured to engage the rearward end of a plurality of different cartridges. The bolt may include an extractor that is configured to engage the rims of the plurality of cartridges and/or an ejector that is configured to bias the cartridge case out of an ejection port of the firearm.

Abstract: A bolt for a firearm is described that can be used to chamber, extract, and/or eject different cartridges that have different outside rim diameters. In one embodiment, the bolt includes a bolt head that is configured to engage the rearward end of a plurality of different cartridges. The bolt may include an extractor that is configured to engage the rims of the plurality of cartridges and/or an ejector that is configured to bias the cartridge case out of an ejection port of the firearm.