Editing Automatic firearm

{{Short description|Firearm that fires continuously while the trigger is depressed}}
[[File:M2 machine gun.jpg|thumb|220px|A [[M2 Browning]] [[machine gun]], surrounded by ejected cartridge cases]]

An '''automatic firearm''' or '''fully automatic firearm''' (to avoid confusion with [[semi-automatic firearm]]s) is a [[self-loading firearm]] that continuously [[Chamber (firearms)|chambers]] and fires [[Cartridge (firearms)|rounds]] when the [[trigger (firearms)|trigger]] mechanism is actuated. The [[action (firearms)|action]] of an automatic firearm is capable of harvesting the excess energy released from a previous discharge to feed a new [[ammunition]] [[cartridge (firearms)|round]] into the [[chamber (firearms)|chamber]], and then igniting the [[propellant]] and discharging the [[projectile]] (either [[bullet]], [[shot (pellet)|shot]], or [[shotgun slug|slug]]) by delivering a [[hammer (firearms)|hammer]] or [[firing pin|striker]] impact on the [[primer (firearms)|primer]].

If ''both'' the feeding and ignition procedures are automatically cycled, the weapon will be considered "fully automatic" and will fire continuously as long as the trigger is kept depressed and the ammunition feeding (either from a [[magazine (firearms)|magazine]] or a [[belt (firearms)|belt]]) remains available.  In contrast, a firearm is considered "[[semi-automatic firearm|semi-automatic]]" if it only automatically cycles to chamber new rounds (i.e. [[self-loading]]) but does not automatically fire off the shot unless the user manually resets (usually by releasing) and re-actuates the trigger, so only one round gets discharged with each individual trigger-pull.<ref name="Carter2012">
{{cite book|last=Carter|first=Gregg Lee
|title= Guns in American Society: An Encyclopedia of History, Politics, Culture, and the Law
|url= https://books.google.com/books?id=oD46JBOhMU0C&pg=PA53|year=2012|publisher=ABC-CLIO
|isbn=978-0-313-38670-1|page= 53
}}
</ref>  A [[burst mode (weapons)|burst-fire]] firearm is an "in-between" of fully and semi-automatic firearms, firing a brief continuous "burst" of multiple rounds with each trigger-pull, but then will require a manual re-actuation of the trigger to fire another burst.

Automatic firearms are further defined by the type of [[Action (firearms)#Autoloading operation|cycling principle]]s used, such as [[recoil operation]], [[blowback (firearms)|blowback]], [[blow forward]], or [[gas operation]].

==Rates of fire==
===Cyclic rate===
Self-loading firearms are designed with varying rates of fire due to having different purposes.  The speed with which a self-loading firearm can cycle through the functions of:

# Fire
# Eject
# Load
# Cock

is referred to as its cyclic rate.  In fully automatic firearms, the cyclic rate is tailored to the purpose the firearm is intended to serve.  Anti-aircraft machine guns often have extremely high rates of fire to maximize the probability of a hit.  In infantry support weapons, these rates of fire are often much lower and in some cases, vary with the design of the particular firearm.  The [[MG 34]] is a [[WWII]]-era machine gun which falls under the category of a "general purpose machine gun". It was manufactured in several variations: with a cyclic rate as high as 1200 rounds per minute, but also in an infantry model which fired at 900 rounds per minute.<ref name="MilFact - MG34">{{cite web|title=Maschinengewehr Modell 34 (MG34) General Purpose Machine Gun (GPMG)|url=http://www.militaryfactory.com/smallarms/detail.asp?smallarms_id=63|website=militaryfactory.com|access-date=3 March 2017}}</ref>

===Effective rate of fire===
Continuous fire generates high temperatures in a firearm's barrel and increased temperatures throughout most of its structure.  If fired continuously, the components of the firearm will eventually suffer structural failure.  All firearms, whether they are semi-automatic, fully automatic, or otherwise, will overheat and fail if fired indefinitely.  This issue tends to present itself primarily with fully automatic fire.  For example, the MG34 may have a calculated cyclic rate of 1200 rounds per minute, but is likely to overheat and fail in the space of one minute of continuous fire.<ref name="Armystudy - M240B Machine Gun">{{cite web|title=M240B - Machine Gun|url=http://www.armystudyguide.com/content/army_board_study_guide_topics/m240b/m240b-study-guide.shtml|website=armystudyguide.com|access-date=3 March 2017|archive-date=18 February 2017|archive-url=https://web.archive.org/web/20170218065331/http://www.armystudyguide.com/content/army_board_study_guide_topics/m240b/m240b-study-guide.shtml|url-status=dead}}</ref>

Semi-automatic firearms may also overheat if continuously fired. Recoil plays a significant role in the time it takes to reacquire one's sight picture, ultimately reducing the effective rate of fire.<ref name="TFB - Sustained Rate of Fire">{{cite web|title=Maintaining a Sustained Rate or Fire|url=http://www.thefirearmblog.com/blog/2012/08/03/maintaining-a-sustained-rate-or-fire/|website=thefirearmblog.com|date=3 August 2012|access-date=3 March 2017}}</ref>

==Automatic firearm types==
[[File:NARA 111-CCV-345-CC37981 25th Infantry Division soldier spraying tree line with M60 fire Operation Cedar Falls 1967.jpg|thumb|A [[United States Army]] soldier laying automatic [[suppressive fire]] with an [[M60 machine gun]] during the [[Vietnam War]]]]

Automatic firearms can be divided into six main categories:

;[[Automatic rifle]]: The standard type of [[service rifle]]s in most modern militaries, usually capable of [[selective fire]]. [[Assault rifle]]s are a specific type of select-fire rifle chambered in an [[intermediate cartridge]] and fed via a high-capacity detachable magazine. [[Battle rifle]]s are similar, but chambered in a [[rifle cartridge|full-powered cartridge]].<ref name="Cutshaw2011">{{cite book|last=Cutshaw|first=Charles Q.|title=Tactical Small Arms of the 21st Century: A Complete Guide to Small Arms From Around the World|url=https://books.google.com/books?id=npHP9aV5rBgC&pg=PA250|date=28 February 2011|publisher=Gun Digest Books|location=Iola, Wisconsin|isbn=978-1-4402-2482-9|page=250}}</ref>
;[[Automatic shotgun]]: A type of [[combat shotgun]] capable of firing shotgun shells automatically, usually also semi-automatically.<ref name="Cutshaw2011"/>
;[[Machine gun]]: A large group of heavier firearms used for [[suppressive fire|suppressive]] automatic fire of rifle cartridges, usually attached to a mount or supported by a bipod. Depending on size, weight and role, machine guns are divided into [[Heavy machine gun|heavy]], [[Medium machine gun|medium]] or [[Light machine gun|light]] machine guns. The ammunition is often [[Belt (firearm)|belt-fed]].<ref name="Cutshaw2011"/>
;[[Submachine gun]]: An automatic, short rifle ([[carbine]]) typically chambered for [[pistol]] cartridges. Today seldom used in military contexts due to a rise in the use of body armor, they are commonly used by police forces and [[close protection]] units in many parts of the world.<ref name="Cutshaw2011"/>
;[[Personal defense weapon]]: A new breed of automatic firearms that combines the light weight and size of the submachine gun with the medium power caliber ammunition of the rifle, thus in practice creating a submachine gun with body armor penetration capability.<ref name="Cutshaw2011"/>
;[[Machine pistol]]: A [[handgun]]-style firearm, capable of fully automatic or [[burst fire]]. They are sometimes equipped with a foldable shoulder stock, to promote accuracy during automatic fire, creating similarities to their submachine gun counterparts. Some machine pistols are shaped similarly to semi-automatics (e.g., the [[Glock 18]], [[Beretta 93R]]). As with SMGs, machine pistols fire pistol caliber cartridges (such as the [[9mm]], [[.40]], [[.45 ACP]] etc.).<ref name="Cutshaw2011"/>

==Burst mode==

[[Burst mode (weapons)|Burst mode]] is an automatic fire mode that limits the number of rounds fired with each trigger pull, most often to three rounds. After the burst is fired, the firearm will not fire again until the trigger is released and pulled again. Burst mode was implemented into firearms due to the inaccuracy of fully automatic fire in combat, and due to suggestions that fully automatic fire has no genuine benefit. Additionally, many militaries have restricted automatic fire in combat due to the ammunition wasted.<ref name="Military.com - Full Auto?">{{cite web|title=Full Auto: Battlefield Necessity or A Waste of Ammo?|url=https://kitup.military.com/2011/12/full-auto-battlefield-necessity.html|website=military.com|access-date=3 March 2017}}</ref>

==Regulation==
{{See also|Gun Control Act of 1968}}
{{Globalize|section|date=October 2022}}
{{More citations needed|section|date=August 2023}}

Possession of automatic firearms tends to be restricted to members of [[military]] and [[law enforcement]] organizations in most developed countries, even in those that permit the civilian use of semi-automatic firearms. Where automatic weapons are permitted, restrictions and regulations on their possession and use may be much stricter than for other firearms.<ref name="Carter2012"/>  In the [[United States]], taxes and strict regulations affect the manufacture and sale of fully automatic firearms under the [[National Firearms Act]] of 1934 and the [[Firearm Owners Protection Act]] of 1986; the latter act banned civilian machine gun ownership, grandfathering in existing legally owned weapons. As legally owned weapons were registered under the NFA this that meant that only previously registered automatic weapons may be purchased. A prospective user must go through an application process administered by the [[Bureau of Alcohol, Tobacco, Firearms and Explosives]] (ATF), which requires a federal tax payment of $200 and a thorough criminal [[background check]]. The tax payment buys a [[revenue stamp]], which is the legal document allowing possession of an automatic firearm. The use of a [[gun trust]] to register with the ATF has become an increasingly popular method of acquisition and ownership of automatic firearms.<ref>{{Cite news |last=Goode |first=Erica |date=2013-02-25 |title=Trusts Offer a Legal Loophole for Buying Restricted Guns |url=https://www.nytimes.com/2013/02/26/us/in-gun-trusts-a-legal-loophole-for-restricted-firearms.html |access-date=2024-06-17 |work=The New York Times |language=en-US |issn=0362-4331}}</ref>

==Similar weapons==
Other similar weapons not usually referred to as automatic firearms include the following:

* [[Autocannon]], which are 15&nbsp;mm or greater in bore diameter and thus considered cannons, not small arms.
* [[Gatling gun]]s, [[multiple-barrel firearm|multiple-barrel]] designs, often used with external power supplies to generate rates of fire higher than automatic firearms.

==See also==
* [[Bump stock]]
* [[Federal Firearms License]]
* [[Firearm action]]
* [[Gun politics]]

==References==
{{Reflist}}

{{Authority control}}

[[Category:Automatic weapons|*]]
[[Category:Firearm actions]]