Receiver (firearms)



In firearms terminology, the firearm frame or receiver is the part of a
firearm A firearm is any type of gun designed to be readily carried and used by an individual. The term is legally defined further in different countries (see #Legal_definitions, Legal definitions). The first firearms originated in 10th-century History ...
which integrates other components by providing
housing Housing, or more generally, living spaces, refers to the construction and housing authority, assigned usage of houses or buildings individually or collectively, for the purpose of Shelter (building), shelter. Housing ensures that members of so ...
for internal action components such as the hammer, bolt or breechblock, firing pin and extractor, and has threaded interfaces for externally attaching ("receiving") components such as the
barrel A barrel or cask is a hollow cylindrical container with a bulging center, longer than it is wide. They are traditionally made of wood Wood is a porous and fibrous structural tissue found in the Plant stem, stems and roots of trees a ...
stock In finance, stock (also capital stock) consists of all the Share (finance), shares by which ownership of a corporation or company is divided.Longman Business English Dictionary: "stock - ''especially AmE'' one of the shares into which owners ...
, trigger mechanism and
iron Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 element, group 8 of the periodic table. It is, Abundance ...
/ optical sights. The receiver is often made of
forge A forge is a type of hearth A hearth () is the place in a home where a fire is or was traditionally kept for home heating and for cooking, usually constituted by at least a horizontal hearthstone and often enclosed to varying degrees b ...
d, machined, or stamped
steel Steel is an alloy made up of iron with added carbon to improve its strength of materials, strength and fracture toughness, fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that ...
aluminium Aluminium (aluminum in American and Canadian English) is a chemical element A chemical element is a species of atoms that have a given number of protons in their atomic nucleus, nuclei, including the pure Chemical substance, substan ...
; in addition to these traditional materials, modern science and engineering have introduced
polymer A polymer (; Greek ''wikt:poly-, poly-'', "many" + ''wikt:-mer, -mer'', "part") is a Chemical substance, substance or material consisting of very large molecules called macromolecules, composed of many Repeat unit, repeating subunits. Due to t ...
s and sintered metal powders to receiver construction.


A barrel can be fixed to the receiver using barrel and receiver action threads or similar methods.

In US law

For the purposes of United States law, the receiver or frame is legally the firearm, and as such it is the controlled part. The definition of which assembly is the legal receiver varies from firearm to firearm, under US law. Generally, the law requires licensed manufacturers and importers to mark the designated receiver with a serial number, the manufacturer or importer, the model and caliber. In addition, makers of receivers are restricted by International Traffic in Arms Regulations. Thus, in the case of a firearm that has multiple receiver parts (such as the AR-15, which has an upper and a lower receiver), the legally controlled part is the one that is serialized. For the AR-15 rifle, the lower receiver assembly is legally considered the actual receiver (although it is functionally a
chassis A chassis (, ; plural ''chassis'' from French ch√Ęssis ) is the load-bearing framework of an artificial object, which structurally supports the object in its construction and function. An example of a chassis is a vehicle frame, the underpa ...
that also houses the separate trigger group); while in the FN-FAL rifle, it is the upper assembly that is serialized and legally considered the receiver. This has led to prosecutors dropping charges against illegal manufacturing of AR-type firearms to avoid court precedents establishing that neither the upper nor the lower receiver individually contain all the components to be legally classified as a firearm.

Unfinished receivers

"Unfinished receivers", also called "80 percent receivers" or "blanks", are partially completed receivers with no serial numbers. Purchasers must perform their own finishing work in order to make the receiver usable. The finishing of receivers for sale or distribution by unlicensed persons is against US law. Because an unfinished 80% receiver is not a firearm, purchasers do not need to pass a background check. The resulting firearm is sometimes called a " ghost gun".

3D printed receivers

, two designs for 3D printable polymer lower receivers for the AR-15 have been released: the AR Lower V5 and the Charon. Like unfinished receivers, 3D-printed ones can be used to produce ghost guns. (Again under US law, the printed receiver itself is a firearm.)


{{Firearm accessories mounting standards Firearm components