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An AR-15-style rifle is any lightweight semi-automatic rifle based on the
Colt AR-15 The Colt AR-15 is a lightweight, magazine-fed, gas-operated semi-automatic rifle. It is a semi-automatic version of the M16 rifle sold for the civilian and law enforcement markets in the United States. Colt's Manufacturing Company currently o ...
design. The original
ArmaLite AR-15 The ArmaLite AR-15 is a select-fire, gas-operated, air-cooled, magazine-fed rifle manufactured in the United States between 1959 and 1964. Designed by American gun manufacturer ArmaLite in 1956, it was based on its AR-10 rifle. The ArmaLite A ...
is a scaled-down derivative of Eugene Stoner's
ArmaLite AR-10 The ArmaLite AR-10 is a 7.62×51mm NATO battle rifle designed by Eugene Stoner in the late 1950s and manufactured by ArmaLite (then a division of the Fairchild Aircraft Corporation). When first introduced in 1956, the AR-10 used an innovative com ...
design. The then Fairchild Engine and Airplane Corporation division
ArmaLite ArmaLite, or Armalite, is an American small arms engineering company, formed in the early 1950s, in Hollywood, California. Many of its products, as conceived by chief designer Eugene Stoner, relied on unique foam-filled fiberglass butt/stock fur ...
sold the patent and trademarks to
Colt's Manufacturing Company Colt's Manufacturing Company, LLC (CMC, formerly Colt's Patent Firearms Manufacturing Company) is an American firearms manufacturer, founded in 1855 by Samuel Colt and is now a subsidiary of Czech holding company Colt CZ Group. It is the su ...
in 1959. After most of Colt's patents for the Colt AR-15 expired in 1977, many firearm manufacturers began to produce copies of the Colt AR-15 under various names. While the patents are expired, Colt retained the trademark of the AR-15 and is the sole manufacturer able to label their firearms as ''AR-15''. The "AR" in Colt AR-15 stands for "ArmaLite Rifle", not " assault rifle". The
Federal Assault Weapons Ban The Public Safety and Recreational Firearms Use Protection Act, popularly known as the Federal Assault Weapons Ban (AWB), was a subsection of the Violent Crime Control and Law Enforcement Act of 1994, a United States federal law which include ...
restricted the sale of the Colt AR-15 and some derivatives in the United States from 1994 to 2004, although it did not affect rifles with fewer listed features. After the term modern sporting rifles was coined in 2009 by the US
National Shooting Sports Foundation The National Shooting Sports Foundation (NSSF) is an American national trade association for the firearms industry that is based in Newtown, Connecticut. Formed in 1961, the organization has more than 8,000 members: firearms manufacturers, distri ...
, a firearms trade association, it was quickly adopted by much of the industry. In the 2010s, AR-15-style rifles became one of the "most beloved and most vilified rifles" in the United States, according to '' The New York Times''. The rifles are controversial in part due to their use in high-profile mass shootings. Promoted as "America's rifle" by the National Rifle Association, AR-15-style rifles' popularity is partially attributable to active restrictions, or proposals to ban or restrict them.


Terminology

A common misconception is that "AR" is an acronym for "assault rifle", perhaps because of the weapon's inclusion in the
Federal Assault Weapons Ban The Public Safety and Recreational Firearms Use Protection Act, popularly known as the Federal Assault Weapons Ban (AWB), was a subsection of the Violent Crime Control and Law Enforcement Act of 1994, a United States federal law which include ...
in 1994, or because the
ArmaLite AR-15 The ArmaLite AR-15 is a select-fire, gas-operated, air-cooled, magazine-fed rifle manufactured in the United States between 1959 and 1964. Designed by American gun manufacturer ArmaLite in 1956, it was based on its AR-10 rifle. The ArmaLite A ...
was originally designed to replace the
M14 rifle The M14 rifle, officially the United States Rifle, Caliber 7.62 mm, M14, is an American selective fire battle rifle chambered for the 7.62×51mm NATO (.308 in) cartridge. It became the standard-issue rifle for the U.S. military in 1959, re ...
in the Vietnam War. The "AR" in AR-15 actually stands for "ArmaLite Rifle", and "AR-15" is most-commonly used to refer ''only'' to the civilian semi-automatic variants of the rifle which lack the
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 discharg ...
function. The AR-15 is closely related to the military
M16 The M16 rifle (officially designated Rifle, Caliber 5.56 mm, M16) is a family of military rifles adapted from the ArmaLite AR-15 rifle for the United States military. The original M16 rifle was a 5.56×45mm automatic rifle with a 20-roun ...
and
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 u ...
rifles, which all share the same core design. Invented by infantry rifle designer
Eugene Stoner Eugene Morrison Stoner (November 22, 1922 – April 24, 1997) was an American firearms designer who is most associated with the development of the ArmaLite AR-15 rifle that was redesigned and modified by Colt's Patent Firearm Company (now known ...
in 1956 for use in the 7.62 NATO caliber
ArmaLite AR-10 The ArmaLite AR-10 is a 7.62×51mm NATO battle rifle designed by Eugene Stoner in the late 1950s and manufactured by ArmaLite (then a division of the Fairchild Aircraft Corporation). When first introduced in 1956, the AR-10 used an innovative com ...
battle rifle A battle rifle is a service rifle chambered to fire a fully powered cartridge. The term "battle rifle" is a retronym created largely out of a need to better differentiate the intermediate-powered assault rifles (e.g. the StG-44, AK-47, M16, ...
, the design features a gas-operated, rotating bolt combined with an integral piston (instead of a conventional
direct impingement Direct impingement is a type of gas operation for a firearm that directs gas from a fired cartridge indirectly (through the barrel, through a gas block, and then through a gas tube) into the bolt carrier or slide assembly to cycle the action. Fi ...
, operating system), and was patented under . A lighter weight
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 w ...
variant of the AR-10 was designed in 1958 for military use and designated the ArmaLite model 15, or AR-15. Due to financial problems and limitations in terms of manpower and production capacity, ArmaLite sold the AR-15 and AR-10 designs and trademarks to Colt in 1959. In 1964, Colt began selling its own version with an improved semi-automatic design known as the
Colt AR-15 The Colt AR-15 is a lightweight, magazine-fed, gas-operated semi-automatic rifle. It is a semi-automatic version of the M16 rifle sold for the civilian and law enforcement markets in the United States. Colt's Manufacturing Company currently o ...
. After Colt's patents expired in 1977, an active marketplace emerged for other manufacturers to produce and sell their own semi-automatic AR-15 style rifles. Some versions of the AR-15 were classified as "
assault weapon In the United States, ''assault weapon'' is a controversial term used to define firearms with specified characteristics. The definition varies among regulating jurisdictions, but usually includes semi-automatic firearms with a detachable magaz ...
s" and banned under the Public Safety and Recreational Firearms Use Protection Act in 1994 within the United States. This act expired in 2004. In 2009, the term "modern sporting rifle" was coined by the
National Shooting Sports Foundation The National Shooting Sports Foundation (NSSF) is an American national trade association for the firearms industry that is based in Newtown, Connecticut. Formed in 1961, the organization has more than 8,000 members: firearms manufacturers, distri ...
for its survey that year as a marketing term used by the firearms industry to describe
modular Broadly speaking, modularity is the degree to which a system's components may be separated and recombined, often with the benefit of flexibility and variety in use. The concept of modularity is used primarily to reduce complexity by breaking a s ...
semi-automatic rifles including AR-15s. Today, nearly every major firearm manufacturer produces its own generic AR-15 style rifle. As Colt continues to own and use the AR-15 trademark for its line of
AR-15 variants This article describes the many variations of the Colt AR-15 and M16 rifle family of weapons produced by Colt's Manufacturing Company. Weapons patterned on the original ArmaLite AR-15 design have been produced by numerous manufacturers and h ...
, other manufacturers must use their own model numbers and names to market their AR-15 style rifles for commercial sale. Under US law, when manufactured with a barrel length less than and without a shoulder stock, it is legally considered a pistol as opposed to being a
short-barreled rifle Short-barreled rifle broadly refers to any rifle with an unusually short barrel. The term carbine describes a production rifle with a reduced barrel length for easier handling in confined spaces. Concern about concealment for illegal purposes h ...
, and is described as an
AR-15 style pistol An AR-15 style pistol is a handgun assembled using an AR-15 style receiver with suitable parts to create a pistol held and fired with one hand. History Colt's Manufacturing Company began marketing the Colt AR-15 self-loading rifle in 1964. Th ...
. The lower receiver alone is legally defined as a firearm under United States federal law. However, this definition may be questionable due to several court rulings (or government dismissals to avoid rulings) that the AR-15 lower receiver does not match the legal definition in 27 CFR § 479.11, though a 2021 case from the Eighth Circuit found otherwise.


Modularity and customization

While most earlier
breech-loading rifles A breechloader is a firearm in which the user loads the ammunition ( cartridge or shell) via the rear (breech) end of its barrel, as opposed to a muzzleloader, which loads ammunition via the front ( muzzle). Modern firearms are generally breec ...
had a single receiver housing both the trigger and reloading mechanism, an innovative feature of the AR-15 was modular construction to simplify substitution of parts and avoid need for
arsenal An arsenal is a place where arms and ammunition are made, maintained and repaired, stored, or issued, in any combination, whether privately or publicly owned. Arsenal and armoury (British English) or armory (American English) are mostl ...
facilities for most repairs of malfunctioning military rifles. A distinctive two-part receiver is used by both military and sporting AR-15 style rifles. As civilian ownership of AR-15 style rifles became sufficient to create a market for improvements, numerous manufacturers began producing aftermarket parts—including parts with features not found on basic AR-15 rifles, and individuals with basic mechanical aptitude can often substitute these pieces for original equipment without needing a gunsmith. Due to the vast assortment of aftermarket parts and accessories available, AR-15 style rifles have also been referred to as "the Swiss Army knife of rifles", "Barbie Dolls for Guys", or "LEGOs for adults". These more or less interchangeable modules are a defining characteristic of AR-15 style rifles. Lower receivers may be bought "stripped"—a single solid part and legally a firearm in the United States, albeit nonfunctional, with no fire control group or lower parts kit installed. End users may install their own choice of fire control group and lower parts kit. A completed lower receiver, compared to a stripped lower receiver, may be visually distinguished by the
trigger guard A trigger guard is a protective loop surrounding the trigger of a firearm designed to prevent unwanted contact with the trigger, which may cause an accidental discharge. Other devices that use a trigger-like actuator mechanism, such as inhalers, c ...
ahead of the detachable
pistol grip On a firearm or other tools, a pistol grip is a distinctly protruded handle underneath the main mechanism, to be held by the user's hand at a more vertical (and thus more ergonomic) angle, similar to the how one would hold a conventional pis ...
, and behind the magazine well capable of holding detachable magazines. The lower receiver holds the trigger assembly including the hammer, and is the attachment point for the
buttstock A gunstock or often simply stock, the back portion of which is also known as a shoulder stock, a buttstock or simply a butt, is a part of a long gun that provides structural support, to which the barrel, action, and firing mechanism are attac ...
. The lower receiver is attached to the upper receiver by two removable pins. Disassembly for cleaning or repair of malfunctions requires disengaging these pins from the upper receiver. Releasing the rear take-down pin allows the receiver to be opened by rotation around the forward pivot pin as a
hinge A hinge is a mechanical bearing that connects two solid objects, typically allowing only a limited angle of rotation between them. Two objects connected by an ideal hinge rotate relative to each other about a fixed axis of rotation: all other ...
. The upper receiver contains the bolt carrier assembly and is attached to the
barrel A barrel or cask is a hollow cylindrical container with a bulging center, longer than it is wide. They are traditionally made of wooden staves and bound by wooden or metal hoops. The word vat is often used for large containers for liquids, ...
assembly. Sights may be attached to the upper receiver or the barrel assembly. A handguard usually encloses the barrel and is attached to the upper receiver, and depending on the handguard, also attached to the barrel's gas block.


Folding stocks

AR-15 style rifles may have folding or collapsible stocks which reduce the overall length of the rifle when folded, although some designs of the stock folding device may not allow the firearm to be fired until unfolded, or only fire once until unfolded. A few manufacturers have made full upper receivers, or even "bufferless" bolt carrier systems where the buffer system is wholly contained in the upper receiver, and therefore does not use the buffer tube, which allows for firing while the stock is in the folded position, or removal of the stock altogether.


Gas systems

The standard design includes a gas block and tube to vent burnt powder gas back into the bolt carrier assembly where it expands in a variable volume chamber forcing the bolt open to eject the spent cartridge case. The buffer spring in the buttstock then pushes the bolt closed after picking up a new cartridge from the magazine. This Stoner bolt and carrier piston system has the disadvantage of venting un-burned smokeless powder residue into the receiver where it may ultimately accumulate in quantities causing malfunctions. Some AR-15 style rifles use an alternative short-stroke gas piston design borrowed from the
ArmaLite AR-18 The ArmaLite AR-18 is a gas-operated assault rifle chambered for 5.56×45mm NATO ammunition. The AR-18 was designed at ArmaLite in California by Arthur Miller, Eugene Stoner, George Sullivan, and Charles Dorchester in 1963 as an alternative t ...
, where a metal rod pushes against the bolt carrier, driven by a piston located just behind the barrel gas port. This piston design keeps the rifle cleaner by not exhausting in to the receiver. Other AR-15 style rifles feature redesigned gas systems so the rifle is "over-the-beach capable", allowing it fire safely as quickly as possible after being submerged in water. The original design features a free-floating
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 sprin ...
. To theoretically reduce the risk of slam-firing, the HK416 and its civilian variant MR556 feature a proprietary firing pin safety in the bolt. Such firing pin safeties may obstruct the upper from working with standard AR-15-type full height hammers located in the fire control group of the lower.


Left-handed users

Most rifles eject spent cartridges from the right side of the receiver away from right handed shooters who place the butt against the right shoulder while sighting with the right eye and using a finger of the right hand to pull the trigger. Right-side ejection is a disadvantage for the third of the population whose left eye is dominant, and for the tenth of the population who are left handed, because holding these rifles against their left shoulder for maximum accuracy may cause the rifle to eject hot spent cases toward the chest, neck, or face of a left handed shooter. When the M16A2 was adopted by the Army in 1986, it incorporated a built-in brass deflector to keep ejected cartridges from hitting the user. Most civilian variants also copy that feature. The modular design of AR-15 style rifles has encouraged several manufacturers to offer specialized parts including leftward ejecting upper receivers and left-handed bolts/bolt carriers for converting right handed AR-15 style rifles for left handed use. Ambidextrous lower receivers, magazine releases, and safety selectors have also been produced, allowing release of the magazine from the left side, closing of the bolt from the right side, and operation of the safety from the right side, respectively.


Calibers

The AR-15 is nominally chambered in
.223 Remington The .223 Remington (designated as the 223 Remington by the SAAMI and 223 Rem by the CIP) is a rimless, bottlenecked rifle cartridge. It was developed in 1957 by Remington Arms and Fairchild Industries for the U.S. Continental Army Command ...
or
5.56×45mm NATO The 5.56×45mm NATO (official NATO nomenclature 5.56 NATO, but often pronounced "five-five-six") is a rimless bottlenecked intermediate cartridge family developed in the late 1970s in Belgium by FN Herstal. It consists of the SS109, L110, a ...
, with the
.223 Wylde chamber A .223 Wylde chamber is a hybrid rifle chamber designed to allow .22 caliber barrels to safely fire both .223 Remington and 5.56×45mm NATO ammunition. While the cartridge dimensions of both rounds are the same, 5.56 NATO loads produce pressures ...
allowing for the safe chambering of both, but many variants have been produced in different calibers such as
.22 LR The .22 Long Rifle or simply .22 LR or 22 (metric designation: 5.6×15mmR) is a long-established variety of .22 caliber rimfire ammunition originating from the United States. It is used in a wide range of rifles, pistols, revolvers, smooth ...
,
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, a ...
,
9×19mm Parabellum The 9×19mm Parabellum (also known as 9mm Parabellum or 9mm Luger or simply 9mm) is a rimless, tapered firearms cartridge. Originally designed by Austrian firearm designer Georg Luger in 1901, it is widely considered the most popular handgu ...
,
6.5mm Grendel The 6.5mm Grendel is an intermediate cartridge jointly designed by British-American armorer Bill Alexander, competitive shooter Arne Brennan (of Houston, Texas) and Lapua ballistician Janne Pohjoispää, as a low-recoil, high-precision rifle cartr ...
, and shotgun calibers. Some of these firearms chambered in smaller calibers such as 9mm or .22 utilize
simple blowback 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. Several blowback systems exist wit ...
or delayed blowback operating principles instead of the default direct impingement/internal-piston based operating system, as insufficient gas pressure or volume is produced by the round to cycle the action, or the simpler blowback system is sufficient and may allow removal of the rear buffer tube and spring.


Compliance with state or local restrictions

Some AR-15 style rifles limit use of detachable magazines to comply with state regulations. Nearly all versions of the civilian AR-15 have a pistol grip like the military versions, but as the pistol grip is generally removable, grips and stocks that comply with various restrictions are available. While AR-15 style rifles are banned in New York City, the FightLite SCR has been explicitly allowed, even though it accepts standard AR-15 upper receivers. The SCR lower receiver differs from the standard AR-15 lower receiver in that it uses a Monte Carlo stock instead of a pistol grip, which may allow it to be legally possessed in jurisdictions with assault weapon restrictions in place. It also uses a proprietary bolt carrier due to the angled buffer tube, and a proprietary fire control group that moves the trigger rearward. A few manufactures offer
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 ...
or
pump action 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 c ...
AR-15 style rifles incapable of semi-automatic fire. These are most commonly marketed in jurisdictions where ownership of semi-automatic rifles is heavily restricted, such as in the United Kingdom. One manufacturer has even invented a non-semi-automatic firearm that fires one shot with each pull of the trigger, although none have yet entered the market.


Comparison to military versions

The semi-automatic civilian AR-15 was introduced by Colt in 1963. The primary distinction between the civilian semi-automatic rifles and the military assault rifles is select fire. Military models are produced with multiple firing modes: semi-automatic fire, fully automatic fire mode and/or
burst fire In automatic firearms, burst mode or burst-fire is a firing mode enabling the shooter to fire a predetermined number of rounds, usually two or three rounds on hand held weapons and 50-100+ on anti-aircraft weapons and autocannons, with a single ...
mode, in which the rifle fires several rounds in succession when the trigger is depressed. Most components are interchangeable between semi-auto and select fire rifles including magazines, sights, upper receiver, barrels and accessories. The military M4 carbine typically uses a barrel. Civilian rifles commonly have or longer barrels to comply with the
National Firearms Act The National Firearms Act (NFA), 73rd Congress, Sess. 2, ch. 757, was enacted on June 26, 1934, and currently codified and amended as . The law is an Act of Congress in the United States that, in general, imposes an excise tax on the manufactu ...
. To prevent a civilian semi-automatic AR-15 from being readily converted for use with the select fire components, several features were changed. Parts changed include the lower receiver, bolt carrier, hammer, trigger, disconnector, and safety/mode selector. The semi-automatic bolt carrier has a longer lightening slot to prevent the bolt's engagement with an automatic sear. Due to a decrease in mass, the buffer spring is heavier. On the select-fire version, the hammer has an extra spur which interacts with the additional auto-sear that holds it back until the bolt carrier group is fully in battery, when the automatic fire is selected. Using a portion of the select fire parts in a semi-automatic rifle will not enable a select fire option (this requires a registered part with the
ATF The Bureau of Alcohol, Tobacco, Firearms and Explosives (BATFE), commonly referred to as the ATF, is a domestic law enforcement agency within the United States Department of Justice. Its responsibilities include the investigation and prevent ...
). Lower receivers that are select-fire are identified by a pinhole above the safety/mode selection switch. As designed by Colt, the pins supporting the semi-auto trigger and hammer in the lower receiver are larger than those used in the military rifle to prevent interchangeability between semi-automatic and select-fire components. The pivot pin may also be slightly larger in diameter.


Production and sales

The first version produced for commercial sale by Colt was the SP1 model AR-15 Sporter in .223 Remington, with a barrel and issued with five-round magazines. Initial sales of the Colt AR-15 were slow, primarily due to its fixed sights and carry handle that made scopes difficult to mount and awkward to use. Military development of the compact M4 carbine encouraged production of a barreled civilian SP1 carbine with a collapsible buttstock beginning in 1977. These carbines have become popular for police use in confined urban spaces, and the collapsible buttstock compensates for the additional thickness of
body armor Body armor, also known as body armour, personal armor or armour, or a suit or coat of armor, is protective clothing designed to absorb or deflect physical attacks. Historically used to protect military personnel, today it is also used by variou ...
. The shorter barrel reduced bullet velocity by about five percent, and bullet energy by about 10%. The shorter barrel required moving the gas port closer to the chamber, exposing the self-loading system to higher pressures and temperatures which increased stress on moving parts like the bolt lugs and extractor. Although Colt offered a heavier 20-inch barrel for improved accuracy beginning in 1986, increased barrel weight may impair
ergonomic Human factors and ergonomics (commonly referred to as human factors) is the application of psychological and physiological principles to the engineering and design of products, processes, and systems. Four primary goals of human factors learnin ...
balance; so shorter barrels have dominated recent rifle production. In the 1990s, sales of AR-15 style rifles increased dramatically, partly as a result of the introduction of the flat top upper receiver (M4 variant) which allowed scopes and sighting devices to be easily mounted as well as new features such as free floating hand guards that increased accuracy. While only a handful of companies were manufacturing these rifles in 1994, by the 21st century the number of AR-15 style rifles had more than doubled. From 2000 to 2015, the number of manufacturers of AR-15 style rifles increased from 29 to an estimated 500. AR-15 style rifles are now available in a wide range of configurations and calibers from a large number of manufacturers. These configurations range from standard full-sizes rifles with barrels, to short carbine-length models with barrels, adjustable length stocks and optical sights, to long range target models with barrels, bipods and high-powered scopes.Evolution of an AR , Gear , Guns & Ammo
. Archives.gunsandammo.com (August 29, 2011). Retrieved on September 27, 2011.
In September 2019, Colt Firearms announced it was discontinuing production of the AR-15 for the consumer market, citing "significant excess manufacturing capacity" across the industry and the company's "high-volume contracts" with military and police forces that were "absorbing all of Colt's manufacturing capacity for rifles". However, in 2020, Colt resumed production of the AR-15, following a surge in demand in the United States consumer market. Estimates vary as to how many of the rifles are owned in the United States. The National Shooting Sports Foundation estimated in 2016 that approximately 5 million to 10 million AR-15 style rifles existed in the U.S. within the broader total of the 300 million firearms owned by Americans.


Hunting

Many hunters prefer using AR-15 style rifles because of their versatility, accuracy, wide variety of available features, and wide variety of calibers (see below). Collapsible stocks are convenient for hunters who pack their rifles into remote hunting locations or for
length of pull Length of pull (sometimes abbreviated as LOP) is the distance from the trigger to the part of a rifle or shotgun which fits against the shoulder of the shooter. Length of pull is an important ergonomic factor for ease of use; and optimum length of ...
adjustments to fit any sized hunter. Construction with lightweight polymers and
corrosion Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engine ...
-resistant alloys makes these rifles preferred for hunting in moist environments with less concern about rusting or warping wood stocks. Positioning of the AR-15 safety is an improvement over traditional
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 ...
hunting rifles. Many states require hunters to use reduced-capacity magazines. If a hunter misses with a first shot, the self-loading feature enables rapid follow-up shots against dangerous animals like
feral pig The feral pig is a domestic pig which has gone feral, meaning it lives in the wild. They are found mostly in the Americas and Australia. Razorback and wild hog are Americanisms applied to feral pigs or boar-pig hybrids. Definition A feral p ...
s or rapidly moving animals like
jackrabbit Hares and jackrabbits are mammals belonging to the genus ''Lepus''. They are herbivores, and live solitarily or in pairs. They nest in slight depressions called forms, and their young are able to fend for themselves shortly after birth. The gen ...
s. Hunters shooting larger game animals often use upper receivers and barrels adapted for larger cartridges or heavier bullets. Several states prohibit the use of
.22 caliber .22 caliber, or 5.6 mm caliber, refers to a common firearms bore diameter of 0.22 inch (5.6 mm). Cartridges in this caliber include the very widely used .22 Long Rifle and .223 Remington / 5.56×45mm NATO. .22 inch is also a popular ...
cartridges like the .223 Remington on large game.


Cartridge variations

Since the upper and lower receivers may be swapped between rifles,
forensic firearm examination Forensic firearm examination is the forensic process of examining the characteristics of firearms or bullets left behind at a crime scene. Specialists in this field try to link bullets to weapons and weapons to individuals. They can raise and ...
of bullets and spent cartridges may reveal distinguishing marks from the barrel and upper receiver group without identifying the lower receiver for which legal records may be available. An individual may use several upper receiver groups with the same lower receiver. These upper receiver groups may have differing barrel lengths and sights and may fire different cartridges. A hunter with a single lower receiver might have one upper receiver with a .223 Remington barrel and telescopic sight for
varmint hunting Varmint hunting or varminting is the practice of hunting vermin — generally small/medium-sized wild mammals or birds — as a means of pest control, rather than as games for food or trophy. The targeted animals are culled because they are con ...
in the open country and another upper receiver with a
.458 SOCOM The .458 SOCOM (11.63×40mm) is a moderately large round designed to work in an AR-15 platform. This is achieved by installing a 458 bolt and barrel. The round offers a supersonic muzzle velocity of and , similar to a light .45-70 but with a m ...
barrel and iron sights for
big-game hunting Big-game hunting is the hunting of large game animals for meat, commercially valuable by-products (such as horns/antlers, furs, tusks, bones, body fat/oil, or special organs and contents), trophy/taxidermy, or simply just for recreation ("s ...
in brushy woodland. The dimensions of upper and lower receivers originally designed for the 5.56×45mm NATO cartridge impose an overall length limit and diameter limits when adapting modules for other cartridges included in this
list of AR platform cartridges The AR platform has become widely popular for makers of hunting and sporting rifles. Although the designations "AR-10" and "AR-15" are respectively trademarks of ArmaLite and Colt, variants of both are made by many manufacturers. The AR-15 rifl ...
. The same magazine in the lower receiver group may hold differing numbers of different cartridges.


Use in crime and mass shootings


United States

Most firearm-related homicides in the United States involve handguns. A 2019 Pew Research study found that 4% of US gun deaths were caused by semi-automatic rifles, a category which includes AR-15 style rifles. According to a 2013 analysis by
Mayors Against Illegal Guns Everytown for Gun Safety is an American nonprofit organization which advocates for gun control and against gun violence. Everytown was created in 2013 when Mayors Against Illegal Guns and Moms Demand Action for Gun Sense in America joined force ...
, 14 out of 93 mass shootings involved
high-capacity magazines A high-capacity magazine (or large-capacity magazine) is a magazine capable of holding more than the usual number of rounds of ammunition for a particular firearm. A magazine may also be defined as high-capacity in a legal sense, based on the ...
or
assault weapons In the United States, ''assault weapon'' is a controversial term used to define firearms with specified characteristics. The definition varies among regulating jurisdictions, but usually includes semi-automatic firearms with a detachable magaz ...
. Nevertheless, AR-15 style rifles have played a prominent role in many high-profile mass shootings in the United States and have come to be widely characterized as the weapon of choice for perpetrators of these crimes. AR-15s or similar rifles were the primary weapons used in half of the 10 deadliest mass shootings in modern American history: the 2012
Sandy Hook Elementary School shooting The Sandy Hook Elementary School shooting occurred on December 14, 2012, in Newtown, Connecticut, United States, when 20-year-old Adam Lanza shot and killed 26 people. Twenty of the victims were children between six and seven years old, and th ...
, the
2017 Las Vegas shooting On October 1, 2017, Stephen Paddock, a 64-year-old man from Mesquite, Nevada, opened fire on the crowd attending the Route 91 Harvest music festival on the Las Vegas Strip in . From his 32nd-floor suites in the Mandalay Bay hotel, he fired m ...
, the 2017
Sutherland Springs church shooting The Sutherland Springs church shooting occurred on November 5, 2017, when Devin Patrick Kelley, of New Braunfels, Texas, perpetrated a mass shooting at the First Baptist Church in Sutherland Springs, Texas. Kelley killed 26 people, wounded 22 ...
, the 2018 Stoneman Douglas High School shooting, and the 2022
Robb Elementary School shooting On May 24, 2022, a mass shooting occurred at Robb Elementary School in Uvalde, Texas, United States, where 18-year-old Salvador Ramos, a former student at the school, fatally shot nineteen students and two teachers, and wounded seventeen othe ...
. Gun expert Dean Hazen and mass murder researcher Pete Blair think that mass shooters' gun choices have less to do with the AR-15's specific characteristics but rather with familiarity and a copycat effect.


Australia

Following the use of a Colt AR-15 rifle in the Port Arthur massacre, the worst single-person shooting incident in Australian history, the country enacted the
National Firearms Agreement The National Firearms Agreement (NFA), also sometimes called the National Agreement on Firearms, the National Firearms Agreement and Buyback Program, or the Nationwide Agreement on Firearms, was an agreement concerning firearm control made by Au ...
in 1996, restricting the private ownership of semi-automatic rifles. ( Category D).


New Zealand

As a result of the
Christchurch mosque shootings On 15 March 2019, two consecutive mass shootings occurred in a terrorist attack on two mosques in Christchurch, New Zealand. The attacks, carried out by a lone gunman who entered both mosques during Friday prayer, began at the Al Noor Mosque ...
with an AR-15 during Friday Prayer on March 15, 2019, the New Zealand government enacted a law to ban semi-automatic firearms, magazines, and parts that can be used to assemble prohibited firearms.


Canada

After the
2020 Nova Scotia attacks On April 18 and 19, 2020, Gabriel Wortman committed multiple shootings and set fires at 16 locations in the Canadian province of Nova Scotia, killing 22 people and injuring three others before he was shot and killed by the Royal Canadian Mou ...
, the deadliest rampage by a single person in Canadian history, Canada banned a class of firearms, including the AR-15.


Partial list of models

*
Barrett REC7 The Barrett REC7 (designation stands for "reliability-enhanced carbine") is an American firearm manufactured as a selective-fire fully-automatic and semi-automatic rifle by Barrett Firearms. It is an M4 carbine utilizing a short-stroke gas pist ...
*
Bushmaster XM-15 The Bushmaster XM-15 series (or XM15) is a line of AR-15 style semi-automatic rifles and carbines previously manufactured by Bushmaster Firearms International, LLC. Variants include the Bushmaster M4-type Carbine, Patrolman series, QRC series, ...
* CAR816 A2 *
Carbon 15 The Carbon 15 is a family of lightweight, magazine-fed pistols, carbines, and rifles developed by defunct United States weapons manufacturer Professional Ordnance, with the design later picked up by Bushmaster Firearms. Overview The Carbon 15 ...
*
Haenel MK 556 The Haenel MK 556 (german: Maschinenkarabiner) is a gas-operated selective-fire 5.56×45mm NATO assault rifle designed by C.G. Haenel in Germany. The MK556 was finalised in September 2020, and it is a fully automatic version of an earlier Ha ...
* Heckler & Koch MR556 *
Remington R5 RGP R5 RGP (Remington Gas Piston) is a carbine that was designed and manufactured by Remington Arms. It is one of many AR-15 type rifles which uses a gas piston operating system in an attempt to improve the reliability of the weapon. User * See ...
*
Ruger SR-556 The SR-556 is a semiautomatic AR-15 style rifle manufactured by U.S. firearms company Sturm, Ruger & Co. The rifle was introduced in 2009 in 223 Remington/5.56×45mm NATO and as a .308 Winchester AR-10 variant in 2013, the SR-762.Gilbert, Gle ...
*
SIG Sauer SIG516 The SIG Sauer SIG516 is a semi-automatic rifle manufactured by SIG Sauer. It is an AR-15 style rifle chambered in 5.56×45mm NATO. Introduced in 2010, the SIG516 was discontinued as of 2019. A variant chambered in 7.62x51mm NATO, the SIG716i, rem ...
*
SIG Sauer SIGM400 The SIGM400 is a family of firearms manufactured by SIG Sauer. The M400 is an air-cooled, direct impingement gas-operated, magazine-fed carbine that is based on the earlier AR-15 rifle. Depending on the variant, it can be chambered for 5.56×45mm ...
*
Smith & Wesson M&P15 The Smith & Wesson M&P15 is an AR-15 style semi-automatic rifle by gun manufacturer Smith & Wesson. Introduced in 2006, the firearm is designed for police use and consumer markets. History "M&P" stands for "Military & Police" and is used to pay ...
*
Springfield Armory SAINT The Springfield Armory SAINT is a series of AR-15 style semi-automatic firearms manufactured by Springfield Armory, Inc. Introduced in November 2016, the series includes rifles, short-barreled rifles (SBRs), and pistols. Variants are marketed un ...


See also

*
List of most-produced firearms This page lists more than 100 small arms designs which have been produced in numbers exceeding one million since the late 18th century. Many more types have been made in the hundreds of thousands. Many of the firearms on this list are military wea ...


References


Further reading

* Stevens, R. Blake and Edward C. Ezell (1994). ''The Black Rifle M16 Retrospective''. Ontario, Canada: Collector Grade Publications. * Bartocci, Christopher R. (2004). ''Black Rifle II The M16 Into the 21st Century''. Ontario, Canada: Collector Grade Publications. {{Colt's Manufacturing Company Weapons and ammunition introduced in 1956 ArmaLite AR-10 derivatives 5.56 mm firearms Modular firearms Semi-automatic rifles Semi-automatic pistols Semi-automatic shotguns AR Rifle Components Gun politics in the United States 6.8mm firearms