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A semi-automatic firearm , also called a self-loading or autoloading firearm (though fully automatic and selective fire firearms are also self-loading), is a repeating firearm whose action mechanism automatically loads a following round of cartridge into the chamber (self-loading) and prepares it for subsequent firing, but requires the shooter to manually actuate the 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 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 produced the first successful design for a semi-automatic rifle in 1885, and by the early 20th century, many manufacturers had introduced semi-automatic shotguns, rifles and pistols.
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-fire operation. Civilian variants such as the AR-15 are generally semi-automatic only.
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. mm ammunition that were fed into the M1894 by a stripper clip.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 rifle designs, he also produced a few semi-automatic pistols, including the Steyr Mannlicher M1894, which employed an unusual blow-forward action and held five rounds of 6.5
In 1902, American gunsmith 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 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.
In 1903 and 1905, the Winchester Repeating Arms Company introduced the first semi-automatic rimfire and centerfire rifles designed especially for the civilian market. The Winchester Model 1903 and Winchester Model 1905 operated on the principle of 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, 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 Model 1907 as an upgrade to the Model 1905, utilizing a blowback system of operation, in calibers such as .351 Winchester. Both the Models of 1905 and 1907 saw limited military and police use.
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 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 which 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 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, 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.
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.
The Soviet AVS-36, 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 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 ]
There are semi-automatic pistols, rifles, and shotguns designed and made as semi-automatic only. Selective-fire 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 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.
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 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). 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.
The mechanism of semi-automatic (or autoloading) firearms is usually what is known as a 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 into the firearm's chamber, ready to fire again once the trigger is pulled.
An 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 guns 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, 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.
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.
Single-shot firearms are firearms that hold only a single round of ammunition, and must be reloaded manually after every shot. The history of firearms began with single-shot designs, then multi-barreled designs appeared, and eventually many centuries passed before multi-shot repeater designs became commonplace.
A semi-automatic rifle is a rifle that fires a single bullet with each pull of the trigger. For comparison, a bolt action rifle requires the user to cycle the bolt manually before they can fire a second time, and a fully automatic rifle, provided it has ammunition, will continue to fire until the trigger is released. Most modern automatic rifles are selective fire, meaning the user can fire semi-automatically if desired.
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.
In firearms terminology, an action is the functional mechanism of a breech-loading firearm that handles the ammunition cartridges, or the method by which that mechanism works. Actions are technically not present on muzzleloaders, as all those are single-shot firearms with a closed off breech with the powder and projectile manually loaded from the muzzle. Instead, the muzzleloader ignition mechanism is referred to as the lock.
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 actually discharge the following shot. As a result, only one round of ammunition is fired each time the trigger is pulled, as the pistol's fire control group disconnects the trigger mechanism from the firing pin/striker until the trigger has been released and reset.
A repeating rifle is a single-barreled rifle capable of repeated discharges between each ammunition reloads. This is typically achieved by having multiple cartridges stored in a magazine and then fed individually into the chamber by a reciprocating bolt, via either a manual or automatic action mechanism, while the act of chambering the round typically also recocks the hammer/striker for the following shot. In common usage, the term "repeating rifle" most often refers specifically to manual repeating rifles, as opposed to self-loading rifles, which use the recoil and/or blowback of the previous shot to cycle the action and load the next round, even though all self-loading firearms are technically a subcategory of repeating firearms.
Lever action is a type of action for repeating firearms that uses a manually operated cocking handle located around the trigger guard area that pivots forward to move the bolt via internal linkages, which will feed/extract cartridges into/out of the chamber and cock the firing pin mechanism. This contrasts to other type of repeating actions such as the bolt-action, pump-action, semi-automatic or automatic/selective-fire actions. A firearm using this operating mechanism is colloquially referred to as a levergun.
An automatic firearm is a 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 to feed a new ammunition round into the chamber, and then ignite the propellant and discharge the projectile by delivering a hammer/striker impact on the primer.
A magazine is an ammunition storage and feeding device for a repeating firearm, either integral within the gun or externally attached. The magazine functions by holding several cartridges within itself and sequentially pushing each one into a position where it may be readily loaded into the barrel chamber by the firearm's moving action. The detachable magazine is sometimes colloquially referred to as a "clip", although this is technically inaccurate since a clip is actually an accessory device used to help loading ammunitions into a magazine.
Pump action or slide action is a repeating firearm action that is operated manually by moving a sliding handguard on the gun's forestock. When shooting, the sliding forend is pulled rearward to eject any expended cartridge and typically to cock the hammer/striker, and then pushed forward to load (chamber) a new cartridge into the chamber. Most pump-action firearms use an integral tubular magazine, although some do use detachable box magazines. Pump-action is typically associated with shotguns, although it has been used in rifles and other firearms as well.
A clip is a device that is used to store multiple rounds of ammunition together as a unit for insertion into the magazine or cylinder of a firearm. This speeds up the process by loading the firearm with several rounds at once, rather than one at a time. There are several types, most made of inexpensive stamped sheet metal, intended to be disposable, though they are often re-used.
Blowback is a system of operation for self-loading firearms that obtains energy from the motion of the cartridge case as it is pushed to the rear by expanding gas created by the ignition of the propellant charge.
A breechblock is the part of the firearm action that closes the breech of a breech loading weapon before or at the moment of firing. It seals the breech and contains the pressure generated by the ignited propellant. Retracting the breechblock allows the chamber to be loaded with a cartridge.
The Mannlicher M1894 was an early blow-forward semi-automatic pistol.
A stripper clip is a speedloader that holds several cartridges together in a single unit for easier and faster loading of a firearm magazine.
Rotating bolt is a method of locking the breech of a firearm closed for firing. Johann Nicolaus von Dreyse developed the first rotating bolt firearm, the "Dreyse needle gun", in 1836. Like the Mauser M 98 or M16, the Dreyse locked using the bolt handle rather than lugs on the bolt head. The first rotating bolt rifle with two lugs on the bolt head was the Lebel Model 1886 rifle. The concept has been implemented on most firearms chambered for high powered cartridges since the 20th century.
Ferdinand Ritter von Mannlicher 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. Later, while making improvements to other inventors prototype designs for rotary-feed magazines, Mannlicher, together with his protégé Otto Schönauer, patented a perfected rotary magazine design, the Mannlicher–Schönauer, which was a commercial and military success.
A self-loading rifle or autoloading rifle is a rifle with an action using a portion of the energy of each cartridge fired to load another cartridge. Self-loading pistols are similar, but intended to be held and fired by a single hand, while rifles are designed to be held with both hands and fired from the shoulder.
A bolt is the part of a repeating, breechloading firearm that blocks the rear opening (breech) of the barrel chamber while the propellant burns, and moves back and forward to facilitate loading/unloading of cartridges from the magazine. The firing pin and extractor are often integral parts of the bolt. The terms "breechblock" and "bolt" are often used interchangeably or without a clear distinction, though usually, a bolt is a type of breechblock that has a nominally circular cross-section.