An automatic firearm is a firearm that automatically extracts and ejects the fired cartridge case, and loads a new case, usually through the energy of the fired round. The term can be used to refer to semi-automatic firearms, which fire one shot per pull of the trigger, or fully automatic firearms, which will continue to load and fire ammunition as long as the trigger (or other activating device) is pressed or until the ammunition is exhausted. "Automatic pistol" or "automatic shotgun" generally refers to a semi-automatic design, while "automatic rifle" more often means a fully automatic or selective fire design.
Fully automatic weapons tend to be restricted to military and police organizations in most developed countries. In the United States, machine guns registered after 1986 have been off the public market since the Firearm Owners Protection Act of 1986. See Gun politics for more information.
Fully automatic firearms are covered in these articles:
- Machine gun
- Submachine gun
- Assault rifle
- Automatic rifle
- Machine pistol
Other similar designs not usually classified as automatic firearms are:
- Autocannon, which are 20 mm in bore diameter or larger and thus considered cannons, not small arms.
- Gatling guns, multi-barrelled bolt-action designs, often used with external power supplies to generate rates of fire higher than automatic firearms.
Similar in appearance but not able to fire in full-auto mode are some semi-automatic rifles. The visual similarity has led to the public usage of the term assault weapon to describe some semi-automatic weapons (as opposed to the proper military usage of the term).
- US patent 1227897 — Automatic gun
 See also
- Firearm action
- Bump fire - a technique to simulate fully-automatic firing with a semi-automatic rifle
- Federal Firearms License
- Gun Control Act of 1968