Receiver (firearms)

Disassembled Mauser action showing partially disassembled receiver and bolt

In firearms terminology, the receiver is the part of a firearm that houses the operating parts. There are many types and styles of firearm receivers. A bolt action or semi-automatic firearm receiver usually contains the bolt carrier group, trigger group, and magazine port.

AR-15 rifles showing their configurations with different upper receivers (stripped-down lower receiver is visible at bottom)

In most handguns, the receiver, or frame, holds the magazine well or rotary magazine as well as the trigger mechanism. It is sometimes called the body of the firearm, while in the context of handguns (revolvers and pistols), it is often called the frame.

The receiver is often made of forged, machined or stamped steel or aluminium; in addition to these traditional materials, modern science and engineering have introduced polymers and sintered metal powders to receiver construction.

In US law

Under United States law, the receiver is the actual firearm itself, and as such it is the controlled part (without which operation is impossible). Generally, the law views the receiver as that part of a firearm housing that has the serial number upon it. Thus, in the case of a firearm that has multiple receivers (such as the AR-15, which has an upper and lower receiver), the legally controlled part is the one that is serialized (the lower, in the AR-15's case).