View source for Semi-automatic firearm

{{Short description|Type of firearm}}
[[File:1973 Colt AR15 SP1.jpg|thumb|The [[Colt AR-15]], a type of [[semi-automatic rifle]]]]
[[File:Unterbrecher einer Feuerwaffe dem Abzug aufsitzend CC BY-SA 4.0 by Grasyl.svg|thumb|A schematic of a semi automatic operation in a hammer fired closed-bolt firearm]]
[[File:Trigger mechanism disconnector in open bolt firearm CC BY-SA 4.0 by Grasyl.svg|thumb|A schematic of a semi-automatic operation in an open-bolt firearm]]

A '''semi-automatic firearm''', also called a '''self-loading''' or '''autoloading firearm''' ([[automatic firearm|fully automatic]] and [[selective fire]] firearms are also variations on [[repeating firearm#Autoloading|self-loading]] firearms), is a [[repeating firearm]] whose [[firearm action|action]] mechanism automatically loads a following round of [[cartridge (firearms)|cartridge]] into the [[chamber (firearms)|chamber]] and prepares it for subsequent firing, but requires the shooter to manually actuate the [[Trigger (firearms)|trigger]] in order to discharge each shot. Typically, this involves the weapon's action utilizing the excess energy released during the preceding shot (in the form of [[recoil]] or high-pressure gas expanding within the [[gun barrel#Bore|bore]]) to unlock and move the [[bolt (firearms)|bolt]], extracting and ejecting the spent cartridge case from the chamber, re-cocking the firing mechanism, and loading a new cartridge into the firing chamber, all without input from the user. To fire again, however, the user must actively release the trigger, and allow it to "reset", before pulling the trigger again to fire off the next round. As a result, each trigger pull only discharges a single round from a semi-automatic weapon, as opposed to a fully automatic weapon, which will shoot continuously as long as the ammunition is replete and the trigger is kept depressed.

[[Ferdinand Ritter von Mannlicher]] produced the first successful design for a semi-automatic rifle in 1885, and by the early 20th century, many manufacturers had introduced [[semi-automatic shotgun]]s, [[semi-automatic rifle|rifle]]s and [[semi-automatic pistol|pistol]]s.

In military use, the semi-automatic [[M1911]] handgun was adopted by the United States Army in 1911, and subsequently by many other nations. Semi-automatic rifles did not see widespread military adoption until just prior to [[World War II]], the [[M1 Garand]] being a notable example. Modern service rifles such as the [[M4 carbine]] are often selective-fire, capable of semi-automatic and automatic or [[Burst mode (weapons)|burst-fire]] operation. Civilian variants such as the [[AR-15 style rifle|AR-15]] are generally semi-automatic only.

==Early history (1885–1945)==

[[File:FSA-1917-detoured.jpg|thumb|The [[Fusil Automatique Modele 1917]] was the first semi-automatic gun that fires [[cartridge (firearms)|cartridges]] to be widely issued in the infantry of any nation's army.]]
The first successful design for a [[semi-automatic rifle]] is attributed to [[Austria]]-born gunsmith [[Ferdinand Ritter von Mannlicher]], who unveiled the design in 1885.<ref name="Jewison2010">{{cite web |last1=Jewison |first1=Glenn |last2=Steiner |first2=Jörg C. |year=2010 |title=Ferdinand Ritter von Mannlicher |url=http://www.austro-hungarian-army.co.uk/biog/mannlicher.htm |website=austro-hungarian-army.co.uk |publisher=Glenn Jewison }}</ref> The Model 85 was followed by the equally innovative Mannlicher Models 91, 93 and 95 semi-automatic rifles.<ref name="Smith1947">{{cite book |last=Smith |first=Walter H.B. |year=1947 |title=Mannlicher Rifles and Pistols: Famous Sporting and Military Weapons |url=https://books.google.com/books?id=AfqingEACAAJ |publisher=Military Service Publishing |isbn=9781258889470 }}</ref> Although Mannlicher earned his reputation with his [[bolt-action]] rifle designs, he also produced a few semi-automatic pistols, including the [[Steyr Mannlicher M1894]], which employed an unusual [[Blow forward|blow-forward action]] and held five rounds of 6.5mm ammunition that were fed into the M1894 by a [[stripper clip]].

===Semi-automatic shotgun===

[[File:Remington 1100 Tactical 8 Rounds.jpg|thumb|right|[[Remington 1100]] Tactical Shotgun in 12 gauge – an example of a semi-automatic [[shotgun]]]]

In 1902, American gunsmith [[John Browning|John Moses Browning]] developed the first successful [[semi-automatic shotgun]], the [[Browning Auto-5]], which was first manufactured by [[Fabrique Nationale de Herstal]] and sold in America under the Browning name. The Auto-5 relied on [[recoil operation|long recoil operation]]; this design remained the dominant form in semi-automatic shotguns for approximately 50 years. Production of the Auto-5 ended in 1998.

===Blowback semi-automatic===

In 1903 and 1905, the [[Winchester Repeating Arms Company]] introduced the first semi-automatic [[Rimfire ammunition|rimfire]] and [[Centerfire ammunition|centerfire]] rifles designed especially for the civilian market. The [[Winchester Model 1903]] and [[Winchester Model 1905]] operated on the principle of [[Blowback (arms)#blowback|blowback]] in order to function semi-automatically. Designed entirely by [[T. C. Johnson]], the Model 1903 achieved commercial success and continued to be manufactured until 1932 when the Winchester Model 63 replaced it.

By the early 20th century, several manufacturers had introduced semi-automatic .22 sporting rifles, including [[Winchester Repeating Arms Company|Winchester]], [[Remington Arms|Remington]], Fabrique Nationale and [[Savage Arms]], all using the direct blow-back system of operation. Winchester introduced a medium caliber semi-automatic sporting rifle, the [[Winchester Model 1907|Model 1907]] as an upgrade to the Model 1905, utilizing a blowback system of operation, in calibers such as [[.351 Winchester Self-Loading|.351 Winchester]]. Both the Models of 1905 and 1907 saw limited military and police use.

===Notable early semi-automatic rifles===

In 1906, [[Remington Arms]] introduced the [[Remington Model 8|Remington Auto-loading Repeating Rifle]]. Remington advertised this rifle, renamed the "Model 8" in 1911, as a sporting rifle. This is a locked-breech, [[long recoil]] action designed by [[John Browning]]. The rifle was offered in .25, .30, .32, and .35 caliber models, and gained popularity among civilians as well as some law enforcement officials who appreciated the combination of a semi-automatic action and relatively powerful rifle cartridges. The Model 81 superseded the Model 8 in 1936 and was offered in [[.300 Savage]] as well as the original Remington calibers.

The first semi-automatic rifle adopted and widely issued by a major military power ([[France]]) was the [[Fusil Automatique Modele 1917]]. This is a locked-breech, gas-operated action that is very similar in its mechanical principles to the future [[M1 Garand]] in the United States. The M1917 was fielded during the latter stages of [[World War I]] but it did not receive a favorable reception. However, its shortened and improved version, the Model 1918, was much more favourably received during the Moroccan [[Rif War (1920)|Rif War]] from 1920 to 1926. The [[Lebel Model 1886 rifle|Lebel]] bolt-action rifle remained the standard French infantry rifle until replaced in 1936 by the [[MAS-36 rifle|MAS-36]] despite the various semi-automatic rifles designed between 1918 and 1935.

Other nations experimented with self-loading rifles between the two World Wars, including the [[United Kingdom]], which had intended to replace the bolt-action [[Lee–Enfield]] with a self-loader, possibly chambered for sub-caliber ammunition, but discarded that plan as the imminence of the Second World War and the emphasis shifted from replacing every rifle with a new design to speeding-up re-armament with existing weapons. The [[Soviet Union]] and [[Nazi Germany]] would both issue successful self-loading and selective-fire rifles on a large scale during the course of the war, but not in sufficient numbers to replace their standard bolt-action rifles.

===Notable gas-operated rifles===

[[File:SKS Flickr.jpg|thumb|right|The SKS is a semi-automatic Russian rifle]]

In 1937, the American [[M1 Garand]] was the first semi-automatic rifle to replace its nation's bolt-action rifle as the standard-issue infantry weapon. The [[gas-operated]] M1 Garand was developed by Canadian-born [[John Garand]] for the U.S. government at the [[Springfield Armory]] in [[Springfield, Massachusetts]]. After years of research and testing, the first production model of the M1 Garand was unveiled in 1937. During [[World War II]], the M1 Garand gave American infantrymen an advantage over their opponents, most of whom were issued slower firing bolt-action rifles.<ref name=Springfield375>{{cite web |author=<!--Staff writer(s); no by-line.--> |year=2011 |title=Firsts: Springfield 375 |url=http://springfield375.org/?p=126 |archive-url=https://web.archive.org/web/20120314004454/http://springfield375.org/?p=126 |archive-date=March 14, 2012 }}</ref>

The [[Soviet Union|Soviet]] [[AVS-36]], [[SVT-40|SVT-38 and SVT-40]] (originally intended to replace the [[Mosin-Nagant]] as their standard service rifle), as well as the German [[Gewehr 43]], were semi-automatic [[Gas-operated reloading|gas-operated]] rifles issued during [[World War II]]. In practice, they did not replace the bolt-action rifle as a standard infantry weapon.

Another gas-operated semi-automatic rifle developed toward the end of World War II was the [[SKS]]. Designed by [[Sergei Gavrilovich Simonov]] in 1945, it came equipped with a [[bayonet]] and could be loaded with ten rounds, using a [[stripper clip]]. However, the SKS was quickly replaced by the [[AK-47]], produced at around the same time, but with a 30-round magazine, and select fire capability. The SKS was the first widely issued weapon to use the [[7.62×39mm]] cartridge.{{Citation needed|date=April 2010}}

== Types ==

[[File:SIG Pro by Augustas Didzgalvis.jpg|thumb|[[SIG Pro]] semi-automatic pistol]]

There are [[semi-automatic pistol]]s, [[semi-automatic rifle|rifle]]s, and [[semi-automatic shotgun|shotgun]]s designed and made as semi-automatic only. [[Selective fire|Selective-fire]] firearms are capable of both full automatic and semi-automatic modes.

Semi-automatic refers to a firearm that uses the force of recoil or gas to eject the empty case and load a fresh cartridge into the firing chamber for the next shot and which allows repeat shots solely through the action of pulling the trigger. A [[Trigger (firearms)#Double-action|double-action]] revolver also requires only a trigger pull for each round that is fired but is not considered semi-automatic since the manual action of pulling the trigger is what advances the cylinder, not the energy of the preceding shot.<ref>{{cite book |last1=Law |first1=Richard |title=The Fighting Handgun: An Illustrated History from the Flintlock to Automatic Weapons |date=1997 |publisher=Arms and Armour |pages=58–59}}</ref>

==Fully automatic compared to semi-automatic==

[[File:Walther P99 9x19mm.png|thumb|right|[[Walther P99]], a [[semi-automatic pistol]] from the late 1990s]]
[[File:Glock 18C.jpg|thumb|[[Glock#Glock 18|Glock 18]], a [[Fully-automatic firearm|fully-automatic]] [[machine pistol]] from the mid-1980s (The picture shown is the Glock 18C)]]

The usage of the term ''automatic'' may vary according to context. Gun specialists point out that the word ''automatic'' is sometimes misunderstood to mean [[Automatic firearm|fully automatic fire]] when used to refer to a self-loading, semi-automatic firearm not capable of fully automatic fire. In this case, ''automatic'' refers to the loading mechanism, not the firing capability. To avoid confusion, it is common to refer to such firearms as an "autoloader" in reference to their loading mechanism.

The term "automatic pistol" almost exclusively refers to a semi-automatic (i.e. not fully automatic) pistol (fully automatic pistols are usually referred to as [[machine pistol]]s). With handguns, the term "automatic" is commonly used to distinguish semi-automatic pistols from revolvers. The term "auto-loader" may also be used to describe a semi-automatic handgun. However, to avoid confusion, the term "automatic rifle" is generally, conventionally, and best restricted to a rifle capable of fully automatic fire. Both uses of the term "automatic" can be found; the exact meaning must be determined from context.

==Auto-loading==

The mechanism of semi-automatic (or autoloading) firearms is usually what is known as a [[closed bolt|closed-bolt]] firing system. In a closed-bolt system, a round must first be chambered manually before the weapon can fire. When the trigger is pulled, only the hammer and [[firing pin]] move, striking and firing the cartridge. The bolt then recoils far enough rearward to extract and load a new cartridge from the [[Magazine (firearms)|magazine]] into the firearm's chamber, ready to fire again once the trigger is pulled.

An [[open bolt|open-bolt]] mechanism is a common characteristic of fully automatic firearms. With this system, pulling the trigger releases the bolt from a cocked, rearward position, pushing a cartridge from the magazine into the chamber, firing the gun. The bolt retracts to the rearward position, ready to strip the next cartridge from the magazine. The open-bolt system is often used in [[submachine gun]]s and other weapons with a high rate of fire. It is rarely used in semi-automatic-only firearms, which can fire only one shot with each pull of the trigger. The closed-bolt system is generally more accurate, as the [[centre of gravity]] changes relatively little at the moment the trigger is pulled.

With fully automatic weapons, the open-bolt operation allows air to circulate, cooling the barrel. With semi-automatic firearms, the closed-bolt operation is preferred, as overheating is not as critical, and accuracy is preferred. Some select-fire military weapons use an open bolt in fully automatic mode and a closed bolt when semi-automatic is selected.

==Legal status==

Many jurisdictions regulate some or all semi-automatic firearms differently than other types.

Various types of semi-automatic weapons were restricted for civilian use in New Zealand after the 2019 [[Christchurch mosque shootings]], in Australia after the 1996 [[Port Arthur massacre (Australia)|Port Arthur massacre]], in Norway after the 2011 [[Utøya shooting]].<ref>{{cite magazine |title=These Countries Restricted Assault Weapons After Just One Mass Shooting |date=2022-05-27 |magazine=[[Time (magazine)|Time]] |archive-url=https://web.archive.org/web/20230728065458/https://time.com/6182186/countries-banned-guns-mass-shooting/ |archive-date=2023-07-28 |url-status=live |url=https://time.com/6182186/countries-banned-guns-mass-shooting/}}</ref> In the United States, the 1994–2004 [[Federal Assault Weapons Ban]] prohibited semi-automatic weapons with certain additional characteristics. As of 2023, several [[Assault weapons legislation in the United States|U.S. states still restrict]] similar types of semi-automatic weapons.

== Examples ==<!-- Please respect alphabetical order -->

{{columns-list|colwidth=30em|
* [[Borchardt C-93]]
* [[Dragunov (SVD-63) sniper rifle]]
* [[Fusil Automatique Modele 1917]]
* [[Gewehr 43]]
* [[CZ-75]]
* [[Glock 17]]
* [[L1A1 SLR]]
* [[Luger pistol]]
* [[M1 Carbine]]
* [[M1 Garand]]
* [[M1911 pistol]]
* [[MAS-49 rifle]]
* [[Meunier rifle]]
* [[Mondragón rifle]]
* [[Remington Model 1100]]
* [[SKS]]
* [[Smith & Wesson M&P15-22]]
* [[SVT-40]]
* [[TEC-9]]
* [[Type 4 rifle]]
}}

== See also == <!-- Please respect alphabetical order -->

{{columns-list|colwidth=30em|
* Main articles
** [[Semi-automatic pistol]]
** [[Semi-automatic rifle]]
** [[Semi-automatic shotgun]]
* Related subjects
** [[AR-15 style rifle]]
** [[Assault rifle]]
** [[Assault weapon]] – certain semi-automatic firearms are classified as assault weapons in some jurisdictions
** [[Designated marksman rifle]]
** [[Personal defense weapon]]
** [[Repeating rifle]]
** [[Single-shot]]
}}

==References==

{{Reflist}}

==External links==
* NPR Audio Report: [https://www.npr.org/templates/story/story.php?storyId=3913023 The Appeal of Semi-Automatic Weapons]

{{DEFAULTSORT:Semi-Automatic Firearm}}
[[Category:Firearm actions]]
[[Category:Firearms]]