![1973 Colt AR15 SP1](https://upload.wikimedia.org/wikipedia/commons/7/7a/1973_Colt_AR15_SP1.jpg)
A semi-automatic firearm, also called a self-loading or autoloading firearm (
fully automatic
An automatic firearm is an auto-loading firearm that continuously chambers and fires rounds when the trigger mechanism is actuated. The action of an automatic firearm is capable of harvesting the excess energy released from a previous discharge ...
and
selective fire firearms are also variations on
self-loading
A semi-automatic firearm, also called a self-loading or autoloading firearm (fully automatic and selective fire firearms are also variations on self-loading firearms), is a repeating firearm whose action mechanism ''automatically'' loads a follow ...
firearms), is a
repeating firearm
A repeating firearm or repeater is any firearm (either a handgun or long gun) that is capable of being fired repeatedly before having to manually reload new ammunition into the weapon.
Unlike single-shot firearms, which can only hold and fir ...
whose
action
Action may refer to:
* Action (narrative), a literary mode
* Action fiction, a type of genre fiction
* Action game, a genre of video game
Film
* Action film, a genre of film
* ''Action'' (1921 film), a film by John Ford
* ''Action'' (1980 fil ...
mechanism ''automatically'' loads a following round of
cartridge
Cartridge may refer to:
Objects
* Cartridge (firearms), a type of modern ammunition
* ROM cartridge, a removable component in an electronic device
* Cartridge (respirator), a type of filter used in respirators
Other uses
* Cartridge (surname), a ...
into the
chamber
Chamber or the chamber may refer to:
In government and organizations
* Chamber of commerce, an organization of business owners to promote commercial interests
*Legislative chamber, in politics
* Debate chamber, the space or room that houses delib ...
(self-loading) and prepares it for subsequent firing, but requires the shooter to ''manually'' actuate the
trigger
Trigger may refer to:
Notable animals and people
;Mononym
* Trigger (horse), owned by cowboy star Roy Rogers
;Nickname
* Trigger Alpert (1916–2013), American jazz bassist
* "Trigger Mike" Coppola (1900–1966), American gangster
;Surname
* Bru ...
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
Recoil (often called knockback, kickback or simply kick) is the rearward thrust generated when a gun is being discharged. In technical terms, the recoil is a result of conservation of momentum, as according to Newton's third law the force r ...
or high-pressure gas expanding within the
bore) to unlock and move the
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, 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
Ferdinand Ritter von Mannlicher (January 30, 1848 – January 20, 1904) was an Austrian engineer and small arms designer. Along with James Paris Lee, Mannlicher was particularly noted for inventing the en-bloc clip charger-loading magazine system ...
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
A semi-automatic shotgun is a repeating shotgun with a semi-automatic action, i.e. capable of automatically chambering a new shell after each firing, but requires individual trigger-pull to manually actuate each shot. Semi-automatic shotguns ...
s,
rifle
A rifle is a long-barreled firearm designed for accurate shooting, with a barrel that has a helical pattern of grooves ( rifling) cut into the bore wall. In keeping with their focus on accuracy, rifles are typically designed to be held with ...
s and
pistol
A pistol is a handgun, more specifically one with the chamber integral to its gun barrel, though in common usage the two terms are often used interchangeably. The English word was introduced in , when early handguns were produced in Europe, an ...
s.
In military use, the semi-automatic
M1911
The M1911 (Colt 1911 or Colt Government) is a single-action, recoil-operated, semi-automatic pistol chambered for the .45 ACP cartridge. The pistol's formal U.S. military designation as of 1940 was ''Automatic Pistol, Caliber .45, M1911'' for th ...
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
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
, the
M1 Garand
The M1 Garand or M1 rifleOfficially designated as U.S. rifle, caliber .30, M1, later simply called Rifle, Caliber .30, M1, also called US Rifle, Cal. .30, M1 is a semi-automatic rifle that was the service rifle of the U.S Army during World War ...
being a notable example. Modern service rifles such as the
M4 carbine
The M4 carbine (officially Carbine, Caliber 5.56 mm, M4) is a 5.56×45mm NATO, gas-operated, magazine-fed carbine developed in the United States during the 1980s. It is a shortened version of the M16A2 assault rifle.
The M4 is extensively ...
are often selective-fire, capable of semi-automatic and automatic or
burst-fire operation. Civilian variants such as the
AR-15 are generally semi-automatic only.
Early history (1885–1945)
![FSA-1917-detoured](https://upload.wikimedia.org/wikipedia/commons/c/c6/FSA-1917-detoured.jpg)
The first successful design for a
semi-automatic rifle
A semi-automatic rifle is an autoloading rifle that fires a single cartridge with each pull of the trigger, and uses part of the fired cartridge's energy to eject the case and load another cartridge into the chamber. For comparison, a bolt-a ...
is attributed to
Austria
Austria, , bar, Östareich officially the Republic of Austria, is a country in the southern part of Central Europe, lying in the Eastern Alps. It is a federation of nine states, one of which is the capital, Vienna, the most populous ...
-born gunsmith
Ferdinand Ritter von Mannlicher
Ferdinand Ritter von Mannlicher (January 30, 1848 – January 20, 1904) was an Austrian engineer and small arms designer. Along with James Paris Lee, Mannlicher was particularly noted for inventing the en-bloc clip charger-loading magazine system ...
, who unveiled the design in 1885.
The Model 85 was followed by the equally innovative Mannlicher Models 91, 93 and 95 semi-automatic rifles.
Although Mannlicher earned his reputation with his
bolt-action
Bolt-action is a type of manual firearm action that is operated by ''directly'' manipulating the bolt via a bolt handle, which is most commonly placed on the right-hand side of the weapon (as most users are right-handed).
Most bolt-action ...
rifle designs, he also produced a few semi-automatic pistols, including the
Steyr Mannlicher M1894
The Mannlicher M1894 was an early blow-forward semi-automatic pistol.
General features
The earliest Ferdinand Mannlicher pistol, manufactured by Fabrique D'Armes de Neuhausen, Switzerland, was designed to be self-loading and to use a special ...
, which employed an unusual
blow-forward action and held five rounds of 6.5 mm ammunition that were fed into the M1894 by a
stripper clip.
Semi-automatic shotgun
![Remington 1100 Tactical 8 Rounds](https://upload.wikimedia.org/wikipedia/commons/0/02/Remington_1100_Tactical_8_Rounds.jpg)
In 1902, American gunsmith
John Moses Browning
John Moses Browning (January 23, 1855 – November 26, 1926) was an American firearm designer who developed many varieties of military and civilian firearms, cartridges, and gun mechanisms many of which are still in use around the world. He ...
developed the first successful
semi-automatic shotgun
A semi-automatic shotgun is a repeating shotgun with a semi-automatic action, i.e. capable of automatically chambering a new shell after each firing, but requires individual trigger-pull to manually actuate each shot. Semi-automatic shotguns ...
, the
Browning Auto-5
The Browning Automatic 5, most often Auto-5 or simply A-5, is a recoil-operated semi-automatic shotgun designed by John Browning. It was the first successful semi-automatic shotgun design, and remained in production until 1998. The name of the s ...
, which was first manufactured by
Fabrique Nationale de Herstal
Fabrique Nationale Herstal (), trading as FN Herstal and often referred to as Fabrique Nationale or simply FN, is a leading firearms manufacturer based in Herstal, Belgium. It is currently the largest exporter of military small arms in Europe.
...
and sold in America under the Browning name. The Auto-5 relied on
long recoil operation; this design remained the dominant form in semi-automatic shotguns for approximately 50 years. Production of the Auto-5 ended in 1999.
Blowback semi-automatic
In 1903 and 1905, the
Winchester Repeating Arms Company
The Winchester Repeating Arms Company was a prominent American manufacturer of repeating firearms and ammunition. The firm was established in 1866 by Oliver Winchester and was located in New Haven, Connecticut. The firm went into receivership ...
introduced the first semi-automatic
rimfire and
centerfire
Two rounds of .357 Magnum, a centerfire cartridge; notice the circular primer in the center
A centerfire cartridge is a firearm metallic cartridge whose primer is located at the center of the base of its casing (i.e. "case head"). Unlike rim ...
rifles designed especially for the civilian market. The
Winchester Model 1903
The Winchester Model 1903 was the first commercially available semi-automatic firearm made by the Winchester Repeating Arms Company.
History
The Winchester Model 1903 was designed by T.C. Johnson, who had joined Winchester in 1885 and had become ...
and
Winchester Model 1905
The Winchester Model 1905 (also known as the Model 05), is a blowback-operated, semi-automatic rifle produced by the Winchester Repeating Arms Company beginning in 1905 and discontinued in 1920. This rifle loads cartridges from a 5 or 10-round ca ...
operated on the principle of
blowback in order to function semi-automatically. Designed entirely by
T. C. Johnson
Thomas Crossley Johnson (1862–1934) was an American firearms designer. The son of a President of the Yale Safe and Iron Company, Johnson was trained as an industrial engineer and worked for several companies prior to employment with the Winchest ...
, 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
Winchester is a City status in the United Kingdom, cathedral city in Hampshire, England. The city lies at the heart of the wider City of Winchester, a local government Districts of England, district, at the western end of the South Downs Nation ...
,
Remington
Remington may refer to:
Organizations
* Remington Arms, American firearms manufacturer
* Remington Rand, American computer manufacturer
* Remington Products, American manufacturer of shavers and haircare products
* Remington College, American c ...
, Fabrique Nationale and
Savage Arms
Savage Arms is an American gunmaker based in Westfield, Massachusetts, with operations in Canada. Savage makes a variety of rimfire and centerfire rifles, as well as Stevens single-shot rifles and shotguns. The company is best known for the ...
, all using the direct blow-back system of operation. Winchester introduced a medium caliber semi-automatic sporting rifle, the
Model 1907 as an upgrade to the Model 1905, utilizing a blowback system of operation, in calibers such as
.351 Winchester
The .351 Winchester Self-Loading (also called .351 SL or .351 WSL) is an American rifle cartridge designed in 1906.
History
Winchester introduced the .351 SL in the Winchester Model 1907 self-loading rifle as a replacement for the Winchester M ...
. 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 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
Recoil operation is an operating mechanism used to implement locked breech, autoloading firearms. Recoil operated firearms use the energy of recoil to cycle the action, as opposed to gas operation or blowback operation using the pressure of the ...
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
The .300 Savage cartridge is a rimless, .30 caliber rifle
A rifle is a long-barreled firearm designed for accurate shooting, with a barrel that has a helical pattern of grooves ( rifling) cut into the bore wall. In keeping with their fo ...
as well as the original Remington calibers.
The first semi-automatic rifle adopted and widely issued by a major military power (
France
France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...
) was the
Fusil Automatique Modele 1917
Fusil may refer to:
*Fusil, a light flintlock musket used by a fusilier
* Fusil (heraldry), a heraldic ordinary similar to a lozenge
* Gerald Fusil, creator of the Raid Gauloises adventure race
{{disambig ...
. This is a locked-breech, gas-operated action which is very similar in its mechanical principles to the future
M1 Garand
The M1 Garand or M1 rifleOfficially designated as U.S. rifle, caliber .30, M1, later simply called Rifle, Caliber .30, M1, also called US Rifle, Cal. .30, M1 is a semi-automatic rifle that was the service rifle of the U.S Army during World War ...
in the United States. The M1917 was fielded during the latter stages of
World War I
World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...
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
The Rif War () was an armed conflict fought from 1921 to 1926 between Spain (joined by History of France, France in 1924) and the Berbers, Berber tribes of the mountainous Rif region of northern Morocco.
Led by Abd el-Krim, the Riffians at ...
from 1920 to 1926. The
Lebel bolt-action rifle remained the standard French infantry rifle until replaced in 1936 by the
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
The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and North ...
, which had intended to replace the bolt-action
Lee–Enfield
The Lee–Enfield or Enfield is a bolt-action, magazine-fed repeating rifle that served as the main firearm of the military forces of the British Empire and Commonwealth during the first half of the 20th century, and was the British Army's sta ...
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
The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen national ...
and
Nazi Germany
Nazi Germany (lit. "National Socialist State"), ' (lit. "Nazi State") for short; also ' (lit. "National Socialist Germany") (officially known as the German Reich from 1933 until 1943, and the Greater German Reich from 1943 to 1945) was ...
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
![SKS Flickr](https://upload.wikimedia.org/wikipedia/commons/2/2f/SKS_Flickr.jpg)
In 1937, the American
M1 Garand
The M1 Garand or M1 rifleOfficially designated as U.S. rifle, caliber .30, M1, later simply called Rifle, Caliber .30, M1, also called US Rifle, Cal. .30, M1 is a semi-automatic rifle that was the service rifle of the U.S Army during World War ...
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
Jean Cantius Garand (; January 1, 1888 – February 16, 1974), also known as John C. Garand, was a Québec-born American designer of firearms who created the M1 Garand, a semi-automatic rifle that was widely used by the U.S. Army and U.S ...
for the U.S. government at the
Springfield Armory
The Springfield Armory, more formally known as the United States Armory and Arsenal at Springfield located in the city of Springfield, Massachusetts, was the primary center for the manufacture of United States military firearms from 1777 until ...
in
Springfield, Massachusetts
Springfield is a city in the Commonwealth of Massachusetts, United States, and the seat of Hampden County. Springfield sits on the eastern bank of the Connecticut River near its confluence with three rivers: the western Westfield River, the ...
. After years of research and testing, the first production model of the M1 Garand was unveiled in 1937. During
World War II
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
, the M1 Garand gave American infantrymen an advantage over their opponents, most of whom were issued slower firing bolt-action rifles.
The
Soviet
The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen nation ...
AVS-36
The AVS-36 (from ''Avtomaticheskaya Vintovka Simonova 1936 model''; russian: Автоматическая винтовка Симонова образца 1936 года (АВС-36)) was a Soviet automatic rifle which saw service in the early year ...
,
SVT-38 and SVT-40 (originally intended to replace the
Mosin-Nagant as their standard service rifle), as well as the German
Gewehr 43
The Gewehr 43 or Karabiner 43 (abbreviated G43, K43, Gew 43, Kar 43) is a 7.92×57mm Mauser caliber semi-automatic rifle developed by Germany during World War II. The design was based on that of the earlier G41(W), but incorporated an improved ...
, were semi-automatic
gas-operated rifles issued during
World War II
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
. 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
Sergey Gavrilovich Simonov ( Russian: Сергей Гаврилович Симонов; 9 April 1894 – 6 May 1986) was a soviet weapons designer; he is considered one of the fathers of the modern assault rifle.
Mostly known for the Samozaryad ...
in 1945, it came equipped with a
bayonet
A bayonet (from French ) is a knife, dagger, sword, or spike-shaped weapon designed to fit on the end of the muzzle of a rifle, musket or similar firearm, allowing it to be used as a spear-like weapon.Brayley, Martin, ''Bayonets: An Illustr ...
and could be loaded with ten rounds, using a
stripper clip. However, the SKS was quickly replaced by the
AK-47
The AK-47, officially known as the ''Avtomat Kalashnikova'' (; also known as the Kalashnikov or just AK), is a gas operated, gas-operated assault rifle that is chambered for the 7.62×39mm cartridge. Developed in the Soviet Union by Russian s ...
, 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
The 7.62×39mm (aka 7.62 Soviet, formerly .30 Russian Short) round is a rimless bottlenecked intermediate cartridge of Soviet origin. The cartridge is widely used due to the worldwide proliferation of Russian SKS and AK-47 pattern rifles, as ...
cartridge.
Types
![SIG Pro by Augustas Didzgalvis](https://upload.wikimedia.org/wikipedia/commons/4/4f/SIG_Pro_by_Augustas_Didzgalvis.jpg)
There are
semi-automatic pistol
A semi-automatic pistol is a type of repeating single-chamber handgun ( pistol) that automatically cycles its action to insert the subsequent cartridge into the chamber (self-loading), but requires manual actuation of the trigger to actuall ...
s,
rifle
A rifle is a long-barreled firearm designed for accurate shooting, with a barrel that has a helical pattern of grooves ( rifling) cut into the bore wall. In keeping with their focus on accuracy, rifles are typically designed to be held with ...
s, and
shotgun
A shotgun (also known as a scattergun, or historically as a fowling piece) is a long gun, long-barreled firearm designed to shoot a straight-walled cartridge (firearms), cartridge known as a shotshell, which usually discharges numerous small p ...
s designed and made as semi-automatic only.
Selective-fire
Selective fire is the capability of a weapon to be adjusted to fire in semi-automatic, fully automatic, and/or burst mode. The modes are chosen by means of a selector switch, which varies depending on the weapon's design. Some selective-fire we ...
firearms are capable of both full automatic and semi-automatic modes.
Semi-automatic refers to a firearm which 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
double-action
Double action (or double-action) refers to one of two systems in firearms where the trigger both cocks and releases the hammer.
*Double-action only (DAO) firearms trigger: The trigger both cocks and releases the hammer. There is no single-action f ...
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.
Fully automatic compared to semi-automatic
![Glock 18C](https://upload.wikimedia.org/wikipedia/commons/3/3b/Glock_18C.jpg)
The usage of the term ''automatic'' may vary according to context. Gun specialists point out that the word ''automatic'' is sometimes misunderstood to mean
fully automatic fire
An automatic firearm is an auto-loading firearm that continuously chambers and fires rounds when the trigger mechanism is actuated. The action of an automatic firearm is capable of harvesting the excess energy released from a previous discha ...
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 its 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 pistols
A machine pistol is an autoloading pistol capable of fully automatic fire. The term can also be used to describe a stockless handgun-style submachine gun. The term is a calque of ''Maschinenpistole'', the German word for submachine guns. Mac ...
). 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
A semi or full-automatic firearm which is said to fire from a closed bolt is one where, when ready to fire, a round is in the chamber and the bolt and working parts are forward. When the trigger is pulled, the firing pin or striker fires th ...
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
A firing pin or striker is a part of the firing mechanism of a firearm that impacts the primer in the base of a cartridge and causes it to fire. In firearms terminology, a striker is a particular type of firing pin where a compressed spring ...
move, striking and firing the cartridge. The bolt then recoils far enough rearward to extract and load a new cartridge from the
magazine
A magazine is a periodical publication, generally published on a regular schedule (often weekly or monthly), containing a variety of content. They are generally financed by advertising, purchase price, prepaid subscriptions, or by a combinatio ...
into the firearm's chamber, ready to fire again once the trigger is pulled.
An
open-bolt
A firearm is said to fire from an open bolt if, when ready to fire, the bolt and working parts are held to the rear of the receiver, with no round in the chamber. When the trigger is actuated, the bolt travels forward, feeds a cartridge from t ...
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
A submachine gun (SMG) is a magazine-fed, automatic carbine designed to fire handgun cartridges. The term "submachine gun" was coined by John T. Thompson, the inventor of the Thompson submachine gun, to describe its design concept as an autom ...
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
In physics, the center of mass of a distribution of mass in space (sometimes referred to as the balance point) is the unique point where the weighted relative position of the distributed mass sums to zero. This is the point to which a force ma ...
changes relatively little at the moment the trigger is pulled.
With fully automatic weapons, 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.
Examples
See also
References
External links
* NPR Audio Report
The Appeal of Semi-Automatic Weapons
{{DEFAULTSORT:Semi-Automatic Firearm
Firearm actions