A semi-automatic rifle is a type of self-loadingrepeating rifle whose action will automatically cycle a new round after each shot, but requires the shooter to manually release the trigger and reset/recock the sear and hammer/striker before pulling again to fire another shot; thus, only one round can be discharged with each pull of the trigger. In contrast, a fully automatic rifle both cycles the cartridges and cycles the hammer/striker automatically. Holding the trigger in the firing position will cause the firearm to continuously fire until the trigger is released or the cartridges are depleted in their entirety.
Operation
Semi-automatic weapons use gas, blow-forward, blowback or recoil energy to eject the spent cartridge after the round has traveled down the barrel, chamber a new cartridge from its magazine, and reset the action. This enables another round to be fired once the trigger is depressed again. Semi-automatic rifles can be efficiently fed by an en-bloc clip and internal magazine, a detachable magazine, or a combination of stripper clip and internal magazine. The self-loading design was a successor to earlier rifles that required manual-cycling of the weapon after each shot, such as the bolt-action rifle or repeating rifles. The ability to automatically load the next round results in an increase in the rounds per minute the operator can fire.
Advantages
The chief advantage of self-loading rifles is the possibility of increasing the number of effective shots fired within any given time period by avoiding the necessity for changing the aiming position of the rifle to manually chamber new cartridges. The actual number of hits per unit of time depends upon the magazine capacity and the availability of detachable magazines, but semi-automatic rifles can typically more than double the number of hits from comparable manually-loaded rifles at close range and increase the number of hits by about 50 percent at longer distances requiring more precise aiming. Firing for prolonged periods may increase this advantage if the manual-loading process causes shooter fatigue. The additional weight of springs and fittings using a portion of the cartridge energy to reload self-loading rifles have the additional advantage of reducing recoil.
Disadvantages
The self-loading mechanism tuned for cartridges of specified dimensions and power may fail to reload dirty or bent cartridges that will otherwise fire satisfactorily. The self-loading mechanism may fail to extract empty low-power cartridge cases useful for training, and high-power cartridges useful at longer ranges may damage the self-loading mechanism. Some self-loading rifles require externally lubricated cartridges vulnerable to dirt adhesion. Failure of the self-loading mechanism to function as designed eliminates the advantage of increased hits per unit of time, and may actually reduce the comparative rate of fire below what is possible with manually-loaded rifles if the self-loading rifle is not designed for convenient manual-loading. The United Kingdom regarded the reliable rate of fire from manually-loaded rifles to be nearly as high as self-loading rifles as recently as World War II. Semi-automatic rifles are uniquely susceptible to slamfire malfunctions caused by abrupt cartridge acceleration during self-loading. Slamfire discharges are unlikely to hit the target, and may cause collateral damage. The complexity of a self-loading mechanism makes self-loading rifles more expensive to manufacture and heavier than manually-loaded rifles. The semi-automatic M1 Garand weighs seven percent more than the manually-loaded M1903 Springfield rifle it replaced. United States development of a self-loading infantry rifle began with the.276 Pederson cartridge in recognition of the difficulties of producing reliable self-loading mechanisms for more powerful cartridges. Although the Garand was ultimately adapted to fire the.30-06 Springfield cartridge at the insistence of General Douglas MacArthur, most subsequent self-loading rifles for infantry use have been chambered for less powerful cartridges to reduce weight making rifles easier to carry.
Magazines
The time required for changing or reloading magazines must be considered- an action that can impose an effective duration limit on the continuous rate of fire of any rifle. High-capacity magazines increase the weight of the rifle, and typically reduce feeding reliability due to the varying spring tension from a full to a nearly empty magazine. Detachable magazines in general are usually less durable than internal magazines.
History
The first successful design for a recoil operated semi-automatic rifle is attributed to Ferdinand Mannlicher, who unveiled the design in 1885. Other non-gas operated semi-automatic models were the Model 85 and Mannlicher Models 91, 93 and 95 rifles. was an early French semi-automatic rifle issued in limited number to the French Armed Forces during World War One.
Blowback semi-automatic
In 1903 and 1905, the Winchester Repeating Arms Company introduced the first low-power blowback semi-automatic rimfire and centerfire rifles. The Winchester Model 1903 and Winchester Model 1905 operated on the principle of blowback to function semi-automatically. Designed 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 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 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 Model 1905 and Model 1907 saw limited military and police use.
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 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. In 1936 the Model 81 superseded the Model 8, and was offered in.300 Savage as well as the original Remington calibers. In 1908 General Manuel Mondragon patented the world's first gas-operated semi-automatic rifle, the Mondragón rifle M1908. Mexico was to the first nation to use a semi-auto rifle in battle in 1911; the rifles were issued to regular troops during the Mexican revolution. This would be the basis of all future semi-automatic firearms to date. After the Mondragon rifle was released, France came out with its own semi-automatic rifle, the Fusil Automatique Modele 1917. This is a locked breech, gas-operated action which is very similar in its mechanical principles to the subsequent M1 Garand in the United States. The M1917 was fielded during the latter stages of WWI, where it did not receive a favorable reception. However its shortened and improved version, the Model 1918, gave complete satisfaction during the Moroccan Rif War from 1920 to 1926. Still, the Lebel bolt-action rifle remained the standard French infantry rifle until replaced in 1936 by the MAS-36, also a bolt action, 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-loading rifle, The UK discarded that plan when the Second World War became imminent, shifting its emphasis to speeding-up re-armament with existing weapons. The Soviet Union and Third Reich both issued effective self-loading and selective-fire rifles on a large scale during the course of that war, but not in sufficient numbers to replace their standard bolt-action rifles.
Gas-operated rifles
In 1937, the American M1 Garand was the first semi-automatic rifle to replace a 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 SovietAVS-36, SVT-38, and SVT-40, as well as the German Gewehr 43, were semi-automatic gas-operated rifles issued during World War II in relatively small numbers. In practice, they did not replace the bolt-action rifle as a standard infantry weapon of their respective nations. 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. It was the first widely issued rifle to use the 7.62×39mm cartridge.
Select examples
Confusion between semi-automatic rifles and automatic rifles
Semi-automatic rifles, while similar in appearance to automatic rifles, are not the same weapons. Automatic rifles are illegal in many jurisdictions for civilian ownership. While some variations of semi-automatic weapons have superficial features which can resemble an automatic or military rifle in some cases, or are simply semi-automatic versions of rifles such as the Heckler & Koch G3, they do not have the same capabilities. In the United States, automatic weapons have been tightly controlled under the National Firearms Act by the Bureau of Alcohol, Tobacco, Firearms and Explosives, requiring a $200 tax stamp and extensive vetting by the ATF. The legality and regulation of semi-automatic rifles is a major issue in firearm politics in the United States, and autoloading rifles are commonly mistaken for automatic rifles. The distinguishing factors of semi-automatic rifles available to the public are mostly limited to appearance and internal operation, as opposed to rate of fire.
Semi-automatic rifles and gun violence in the U.S.
Semi-automatic rifles have become a defined topic in the American gun debate, mostly due to their aggressive appearances and their use in several prominent shootings. Many on the pro-gun side argue that this focus is unwarranted, as rifles are used in only a handful of homicides in the United States per year; this includes both semi-automatic rifles as well as other varieties of rifles. Since 1999, there have been a total of 115 mass shooting incidents: defined as a shooting incident taking place in a public place where four or more people, not including the shooter, were killed by a gun. Of the 115 mass shootings in the United States from 1999 to September 2019, semi-automatic rifles were only used in 32 of them. Studies do suggest however, that when semi-automatic rifles are used, particularly in a mass shooting, the number of casualties in a single incident does tend to increase. The 2017 Las Vegas shooting, for instance, which is the deadliest mass shooting in the United States to date, was largely carried out by modified semi-automatic rifles. While the number of casualties in a single incident may be higher when a semi-automatic rifle is used, handguns make up more than 64% of all firearm related homicides in the United States.
Firing at targets to improve accuracy was commonplace before the advent and widespread ownership of firearms, and dated to the spread and adaptation of archery. While target shooting was first widely employed as training for archers and marksmen, it later evolved into sports such as target shooting, sport shooting and marksmanship. Target shooting progressed with the rapidly spreading private ownership of firearms in the 1700 and 1800s, primarily due to the demand for judicious marksmanship in conflicts like the Civil War, and has established itself as a sport with a firm foundation. Today, semi-automatic rifles are one of the more popular firearms in sport shooting. There are a great variety of types of sport shooting, ranging from rapid fire shooting, target shooting, which is predominantly accuracy based, and distance shooting. Shooting clubs in America became increasingly commonplace in the 1830s, and have since grown in popularity. Semi-automatic rifles are commonly used in sport shooting events because of their accuracy, versatility, and their light weight- which has invited more people, specifically women and children, to compete as well.
Hunting
Semi-automatic rifles have grown in status among hunters. Many hunters are adopting semi-automatic rifles, particularly AR-15 style rifles to take advantage of their compact design, effectifvely making it easier to traverse rugged terrain while tracking a target. Semi-automatic fire greatly assists in maintaining one's sight picture, proving especially helpful when follow-up shots are required. Due to their demand, the manufacturers of semi-automatic firearms have greatly increased the effective firing distance of their products, compared to the first semi-automatics to have hit the market. These features have proven ground breaking in sport hunting.
Self defense
Semi-automatic rifles are an excellent candidate for self-defense. Most semi-automatic rifles are rather lightweight and simple to operate, without compromising accuracy. It has been speculated that some styles of semi-automatic rifles may be perceived as more intimidating in appearance to a potential threat, possible descreasing a firearm owner's odds of actually needing to fire their weapon in the event of a home invasion or any other potentially threatening situation. Most semi-automatic rifles also have sights which can be adjusted for range. Such a feature proves particular useful if the rifle is to be used in both home breaching/defensive roles and long range/offensive roles.
