AR-15

Modified AR-15

The AR-15 is a lightweight, intermediate cartridge, magazine-fed, air-cooled Armalite Rifle with a rotating lock bolt, actuated by a piston within the bolt carrier or by conventional long/short stroke piston operation. It has been produced in many different versions, including numerous semi-automatic and select fire variants. It is manufactured with extensive use of aluminum alloys and synthetic materials.

The AR-15 was first built in 1959 by ArmaLite as a small arms rifle for the United States armed forces. Because of financial problems, ArmaLite sold the design to Colt. After some modifications, the redesigned rifle was adopted as the M16 rifle. In 1963, Colt started selling the semi-automatic version of the rifle for civilians as the Colt AR-15. Although the name "AR-15" remains a Colt registered trademark, variants of the firearm are made, modified, and sold under various names by multiple manufacturers.

History

The AR-15 is based on the 7.62 mm AR-10 designed by Eugene Stoner, Robert Fremont, and L. James Sullivan of the Fairchild Armalite corporation.^[11] The AR-15 was developed as a lighter, 5.56 mm version of the AR-10. The "AR" in all ArmaLite pattern firearms simply stands for "ArmaLite Rifle",^[12] and can be found on most of the company's firearms: AR-5, a .22 caliber rifle; the AR-7, another .22 caliber; the AR-17 shotgun; the AR-10 rifle; and the AR-24 pistol.^[13][14]

1973 Colt AR-15 SP1 rifle with 'slab side' lower receiver (lacking raised boss around magazine release button) and original Colt 20-round box magazine

In 1959, ArmaLite sold its rights to the AR-10 and AR-15 to Colt. After a tour by Colt of the Far East, the first sale of AR-15s was made to Malaya on September 30, 1959, and Colt manufactured their first 300 AR-15s in December 1959.^[15] Colt marketed the AR-15 rifle to various military services around the world. After modifications (most notably the relocation of the charging handle from under the carrying handle to the rear of the receiver), the redesigned rifle was adopted by the United States military as the M16 rifle.^[16]

In 1963, Colt started selling the semi-automatic version of the M16 rifle as the Colt AR-15 for civilian use and the term has been used to refer to semiautomatic-only versions of the rifle since then.^[17] Colt continued to use the AR-15 trademark for its semi-automatic variants (AR-15, AR-15A2) which were marketed to civilian and law-enforcement customers. The original AR-15 was a very lightweight weapon, weighing less than 6 pounds with empty magazine. Later heavy-barrel versions of the civilian AR-15 can weigh upwards of 8.5 lb.^[18]

Today, the AR-15 and its variations are manufactured by many companies and are popular among civilian shooters and law enforcement forces around the world due to their accuracy and modularity (for more history on the development and evolution of the AR-15 and derivatives see M16 rifle).

The trademark "AR15" or "AR-15" is registered to Colt Industries, which maintains that the term should only be used to refer to their products. Other AR-15 manufacturers make AR-15 clones marketed under separate designations, although colloquially these are sometimes referred to by the term AR-15.

Some notable features of the AR-15 include:

• Aircraft grade forged 7075-T6 aluminum receiver that is lightweight, highly corrosion-resistant, and machinable.
• Modular design that allows the use of numerous accessories such as after market sights, vertical forward grips, lighting systems, night vision devices, laser targeting devices, muzzle brakes/flash hiders, sound suppressors, bipods, etc., and makes repair easier.
• Straight-line stock design that eliminates the fulcrum created by traditional bent stocks, reducing muzzle climb.
• Small caliber, accurate, lightweight, high-velocity round (.223/5.56×45mm)
• Easily adapted to fire numerous other rounds
• Front sight adjustable for elevation
• Rear sight that is adjustable for windage (most models) and elevation (some models)
• Wide array of optical aiming devices available in addition to or as replacements of iron sights
• Stoner gas system (as designed), with short or long stroke gas piston, or direct blowback operating systems available
• Synthetic pistol grip and butt stock that do not swell or splinter (regulated in some states)
• Various magazine capacities, ranging from 10 to 30-round or more
• Ergonomic design that makes the charging handle, selector switch (which also engages the safety), magazine release, and bolt catch assembly easy to access.
• 4 MOA accuracy

AR-15 sight picture

Semi-automatic AR-15s for sale to civilians are internally different from the full automatic M16, although nearly identical in external appearance. The hammer and trigger mechanisms are of a different design. The bolt carrier and internal lower receiver of semi-automatic versions are milled differently, so that the firing mechanisms are not interchangeable. The design changes were done to satisfy United States Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) requirements that civilian weapons may not be easily convertible to full-automatic. Even so, the full automatic M16 bolt carrier is now the most popular type, and is approved by ATF.

In the late 1970s and early 1980s, items such as the "Drop In Auto Sear" or "lightning link," made conversion to full automatic straightforward. In some cases such conversion did require machining the lower receiver with use of a mill, as well as the substitution of a M16 bolt carrier group.^[19][20] Such modifications, unless made using registered and transferable parts prior to May 19, 1986, are illegal. The Firearm Owners Protection Act in 1986 has redefined a machine gun to include individual components with which a semi-automatic firearm can be converted to full-automatic, based on a 1981 ATF ruling on machine gun parts. Since 1993, the bolt carrier groups used in AR-15 type rifles for civilians have employed additional measures to prevent modification to full auto. Colt AR-15's use a metal alloy wall separating the fire control group from the sear, preventing use of full automatic parts.

Automatic variants have a three-position rotating selective fire switch, allowing the operator to select between three modes: safe, semi-automatic, and either automatic or three-round burst, depending on model. Civilian Colt AR-15 models do not have three-round burst or automatic settings; they can only be fired as a semi-automatic, and are therefore not selective fire weapons. In semi-automatic-only variants, the switch only selects between safe and fire modes. Some other manufacturers may mark their rifles with three-positions for collectors and re-enactors, though the guns will not fire in those modes. Weapons modified to full automatic using a lightning-link are capable only of full automatic fire unless a special full automatic fire select mechanism and a modified selector-switch are substituted.^[19] Many AR-15's made before 1986 were converted to be M16's by gunsmiths who legally turned them into Form One rifles in the U.S.^[21] A converted AR will have an auto sear in a lower receiver marked as an AR-15.^[21]

Today, while the civilian manufacture, sale, and possession of post-1986 select-fire AR-15 variants is prohibited, it is still legal to sell templates, tooling, and manuals to complete such conversion. These items are typically marketed as being "post-sample" materials for Federal Firearm Licensees, and are used in the manufacturing of select-fire variants of the AR-15 for law enforcement, military and overseas customers.^[22]

Operating mechanism

Diagram of an M16 rifle, firing

U.S. Patent 2,951,424 describes the cycling mechanism used in the AR-15. The bolt carrier acts as a movable cylinder, and the bolt itself acts as a stationary piston. This mechanism often is called "direct gas impingement", but it differs from prior gas systems.

Gas is tapped from the barrel as the bullet moves past a gas port located above the rifle's front sight base. The gas rushes into the port and down a gas tube, located above the barrel, which runs from the front sight base into the AR-15's upper receiver. Here, the gas tube protrudes into a "gas key" (bolt carrier key), which accepts the gas and funnels it into the bolt carrier.

At this point, the bolt is locked into the barrel extension by locking lugs, so the expanding gas forces the bolt carrier straight backward a short distance. As the bolt carrier moves toward the butt of the gun, the bolt cam pin, riding in a slot on the bolt carrier, forces the bolt to rotate and thus unlocks it from the barrel extension. Once the bolt is fully unlocked it begins its rearward movement along with the bolt carrier. The bolt's rearward motion extracts the empty cartridge case from the chamber. As soon as the neck of the case clears the barrel extension, the bolt's spring-loaded ejector forces it out the ejection port in the side of the upper receiver.

Behind the bolt carrier is a plastic or metal buffer, which rests in line with a return spring. The buffer spring begins to push the bolt carrier and bolt back toward the chamber once it is compressed sufficiently. A groove machined into the upper receiver guides the bolt cam pin and prevents it and the bolt from rotating into a closed position. The bolt's locking lugs push a fresh round from the magazine as the bolt moves forward. The round is guided by feed ramps into the chamber. As the bolt's locking lugs move past the barrel extension, the cam pin twists into a pocket milled into the upper receiver. This twisting action follows the groove cut into the carrier and forces the bolt to twist and "lock" into the barrel extension.

Variants

Colt AR-15 Sporter SP1 Carbine

The AR-15 rifle is available in a wide range of configurations from a large number of manufacturers. These configurations range from short carbine-length models with features such as adjustable length stocks and optical sights, to heavy barrel models.

Due to the rifle's modular design, one upper receiver can quickly and easily be substituted for another. There are many aftermarket upper receivers that incorporate barrels of different weights, lengths and calibers. Some available calibers for the AR-15 are the .223 Remington/5.56×45mm, .300 Blackout, 7.62×39mm, 5.45×39mm, .45 ACP, 5.7×28mm, 6.5mm Grendel, 6.8mm Remington SPC,^[23] .50 Beowulf, .50 BMG, and .458 SOCOM.^[24]

Colt AR-15 A3 Tactical Carbine. Rifle is shown with a CQB Tactical Sling and a Colt 4×20 scope.

When installing a new complete upper receiver, particularly one designed to handle a different caliber of ammunition (i.e., other than .223 Remington or 5.56×45mm NATO), some modification to the lower receiver may be required, depending on the particular conversion. For example, a conversion to 9 mm typically would involve the installation of a magazine well block (to accommodate a typical 9 mm magazine, such as Uzi or Colt SMG), replacing the .223 hammer with one designed for 9 mm ammunition, and depending on the original stock, replacing the buffer, action spring and stock spacer with those designed for the new 9 mm AR-15 configuration. The 9mm cartridge fires from an unlocked breech, or straight blow-back—rather than a locked breech, because the spring and bolt provide enough weight to allow this type of functioning. These guns do not utilize the direct gas impingement method of operation like the original.

5.56×45mm NATO compared to .50 Beowulf cartridges.

Some AR-15s like the POF, LWRCI, H&K, Sturm Ruger, SIG Sauer, United Defense Manufacturing Corporation, CMMG, and Adams Arms offerings replace the DGI (direct gas impingement) operating system with a short stroke/long stroke gas piston system. These guns usually have modified bolt carriers, gas keys, and gas blocks. When fired, DGI systems dump high pressure hot gas through the gas tube to the bolt carrier key and into the bolt carrier group. This can rapidly heat up the bolt carrier group and cause excessive fouling, one of the main complaints about the design. Gas piston operating systems alleviate these problems, but can cause other issues, such as carrier tilt, which can lead to increased bolt fractures.

Some manufacturers offer upper and lower receivers machined from a solid billet (block) of aluminum as opposed to an aluminum forging. Forgings typically having a comparatively higher strength to weight ratio than billet-based receivers.

Upper receivers that combine a railed hand guard and upper receiver into one unit are made by companies like Colt's Manufacturing Company, Lewis Machine and Tool (LMT MRP), POF-USA, and VLTOR. This is done to provide a continuous rail section that runs along the top of the gun from the weapon's charging handle to the front sight/gas block. This rail section is used for the mounting of sights, laser aiming devices, night vision devices, and lighting systems.

A side charging upper receiver has been developed by LAR Grizzly. Blackwood Arms has also developed a side charging upper receiver.^[25] The charging handle can be had in a left side, right side, or ambidextrous configuration. The side charging handle is attached to the bolt carrier, making it a reciprocating design. The handle thus can be used as a forward assist device.

Early models had a 1:14 rate of twist for the original 55 grain (3.6 g) bullets. This was changed to 1:12 when it was found that 1:14 was insufficient to stabilize a bullet when fired in cold weather. Most recent rifles have a 1:9 or 1:7 twist rate. There is much controversy and speculation as to how differing twist rates affect ballistics and terminal performance with varying loads, but heavier, longer projectiles tend to perform better with faster rifling rates.^[26] Additionally, the various non .223 / 5.56 calibers have their own particular twist rate, such as 1:10, 1:11 and 1:12 for 6.8×43mm SPC, 1:10 for 7.62×39mm, 1:9 for the 6.5 Grendel, and 1:8 for .300 Blackout.

A Colt AR-15 on display at the National Firearms Museum. This example is fitted with an early waffle-patterned 20-round magazine.

Standard issue magazines are 20- or 30-round staggered-column magazines and traditional box magazines exist in 40- and 45-round capacities. Drum magazines with 90- and 100-round capacities, such as Beta C-Mags are available, as well. Low-capacity magazines, usually of a 5- or 10-round capacity, are available to comply with some areas' legal restrictions, for hunting, and for benchrest shooting, where a larger magazine can be inconvenient. Surefire is now offering extended capacity magazines in 60- and 100-round capacity configurations. These are of a staggered column design, dubbed casket magazines due to their shape. Usable magazines have been constructed from a variety of materials including steel, aluminum, and high-impact plastics.

Muzzle devices

Most AR-15 rifles have a barrel threaded in 1⁄2"-28 threads to incorporate the use of a muzzle device such as a flash suppressor, sound suppressor or muzzle brake.^[27] The initial design had three tines or prongs and was prone to breakage and getting entangled in vegetation. The design was later changed to close the end to avoid this problem. Eventually, on the A2 version of the rifle, the bottom port was closed to reduce muzzle climb and prevent dust from rising when the rifle was fired in the prone position.^[28] For these reasons, the US military declared this muzzle device a compensator, but it is more commonly known as the "GI" or "A2" flash suppressor.^[29]

Flash suppressors are designed to reduce the muzzle flash from the weapon to preserve the shooter's night vision. A flash suppressor does not improve the ballistic performance of a rifle or make it more lethal, but some jurisdictions have banned or severely restrict usage of flash suppressors. In most of these areas, AR-15 shooters have installed muzzle brakes or compensators on their rifles.

The threaded barrel allows sound suppressors with the same thread pattern to be installed directly to the barrel, however this can result in complications such as being unable to remove the suppressor from the barrel.^[30] A number of suppressor manufacturers have turned to designing "direct-connect" sound suppressors which can be installed over an existing flash suppressor as opposed to using the barrel's threads.^[30]

Legal status of civilian ownership

Australia

AR-15 rifles, like all semi-automatic rifles, are subject to strong restrictions of ownership in all states and territories in Australia. The only means of legally owning an AR-15-type rifle in Australia today beyond law enforcement is to have a Category D Firearms License (e.g. a professional animal culler), to have a Firearms Collector's License and the firearm deactivated (with the barrel plugged up and the action welded shut), or converted to blank fire if one is a member of a military re-enactment organization.

Restrictions on semi-automatic rifles were introduced in 1996 in response to the Port Arthur massacre – one of the firearms used was an AR-15. Previously, AR-15 rifles were legal to own in Queensland and Tasmania.

As a consequence to stricter legal requirements to semi-automatic firearms; AR-15 type rifles became too expensive for television and film production with the requirement to destroy or export imported semi-automatic rifles after use. Warwick Firearms & Militaria[31] , a Melbourne prop maker, self-manufactures blank firing AR-15-type, WFM4 rifles locally with approximately three dozen having been sold.^[32]

Austria

In Austria, semi-automatic centerfire rifles have to be classified as sporting or hunting firearms in order to obtain civilian-legal status. After this classification, they are considered "category B" firearms, which means that holders of gun licenses may own them. These licenses are may-issue items if the applicant specifies a valid reason (self-defense at home for example is considered valid by law in any case), passes a psychological test and attends a gun-basics course.

Three AR-15 manufacturers, all producing in Germany have had versions of their AR-15 models successfully classified as class B weapons. These Austrian versions differ slightly from the original design in order to ensure that no military full-auto trigger, bolt and barrel may be installed. Additionally, bayonet lugs and flash hiders are prohibited on semi-automatic rifles while muzzle brakes and compensators are legal. There is no minimum length for barrels, therefore even barrel lengths as short as 7.5" are possible.

Belgium

Semi-automatic firearms and thus AR-15 type rifles are legal to own, if in possession of the correct license.

Canada

The Government of Canada classifies the AR-15 (and its variants) as a restricted firearm. For anyone wanting to lawfully own an AR-15, they must obtain a Possession and Acquisition License (PAL) valid for restricted firearms (RPAL) and then each acquisition of a restricted class firearm is subject to approval by the Chief Firearms Officer (CFO) of the would-be buyer's province of residence.^[33][34] With the introduction of strict gun control measures by former Prime Minister Jean Chretien (Bill C-68), the AR-15 had originally been intended to be classified as a prohibited firearm, making it impossible to privately own one. However, due to the presence of nationwide Service Rifle target shooting competitions, the AR-15 was granted a sporting exception.

As with all Restricted firearms (including most pistols, some shotguns, and some rifles) AR-15s are allowed to be fired only at certified firing ranges since the CFOs of all provinces and territories have agreed to issue ATTs (Authority To Transport) for these guns only to certified ranges. Since owners cannot legally take these guns anywhere else that shooting is allowed, they can in effect only shoot them on certain ranges. In order to legally own and transport a Restricted firearm, the firearm must be registered with the Royal Canadian Mounted Police Canadian Firearms Program and must apply for an Authorization to Transport (or ATT) from the Chief Firearms Officer (CFO) for their province or territory. Additionally, the firearm must be unloaded, deactivated by a trigger or action lock, and be in a locked, opaque "hard to break into" container during transport.^[35] ("Hard to break into" is not legally defined within the Canadian firearms act or the CCC.)

The issuance of ATTs varies considerably from province to province, and is generally reflective of a particular province's political and social levels of acceptance toward gun ownership. In Ontario the "policy" of the CFO (currently Chris Wyatt) for obtaining an ATT for restricted firearms is to become a member of a range. However policy is not law and when challenged they have no choice but to either issue the ATT requested or do a formal refusal which can be challenged (for free) in court since they must abide by the law. It is not legal for them to refuse on the phone since the only acceptable method for that is in writing as per FA s.72(1).^[36]

However, in Alberta and Saskatchewan, where firearms ownership is widely accepted, generally a single ATT is promptly issued that allows citizens to transport firearms to border crossings, gunsmiths, and shooting ranges. Firearms transfers in provinces such as Ontario, Quebec and some others can take up to 6 months to process.

Czech Republic

The Czech Firearms Act categorizes semi-automatic rifles as "Class B" firearm. Class B firearms are available to anyone with a firearm license, which is shall issue (i.e. cannot be denied) subject to fulfillment of the act's conditions (e.g. clean criminal record, no history of mental illness, no DUI in past three years, passing gun license exam). Prior to purchase, a licensed civilian needs to fill a permit to "buy, possess and carry", which is also shall issue and takes about 15 minutes to process, with the local police station. The purchase permit is valid for one year. Any firearm must be registered with the police within ten days of purchase.

There is no magazine capacity limitation for sport or self-defense use. On the other hand, only magazines with maximum capacity of two rounds may be used for hunting. AR-15 as well as any other semi-automatic rifle may be carried loaded for self-defense only in concealed manner. Hunters may carry the firearm openly to and from the area of a hunt in way preventing its immediate use (i.e. unloaded, with empty magazines). There are no limitations on flash hiders and bayonets, while lasers and silencers fall into "Class A" category requiring a may-issue permit (usually difficult to obtain). Night vision falls also into "Class A" category; however, the permit process for it has been simplified since 2014 for hunters. Moreover, in 2015 the Ministry of Agriculture started subsidizing up to 80% of purchase price of night vision equipment to hunters who shoot more than 20 wild boar a year in order to cull boar infestation.

AR-15s are quite popular in the Czech Republic. As of 2015, there are three manufacturers of AR-15 in the Czech Republic: V-AR, Proarms Armory and LUVO.

Finland

In Finland, possession of semi-automatic rifles, including the AR-15, is legal, provided that the rifle's owner acquires a permit for owning one. A license is required for each individual firearm and there needs to be a specific reason for ownership such as participation in the shooting sports and hunting. In Finland maximum magazine capacity in hunting is 3 rounds. But in addition a hunter can have 1 round chambered which brings their direct ammo capacity up to 4 rounds. There is no magazine capacity limit on guns for target or other sporting shooting.

Germany

The AR-15, like other semi-automatic rifles, is categorized as a "Class B" firearm. Possession of semi-automatic rifles, including the AR-15, is legal with a gun license (Waffenbesitzkarte). These licenses are shall-issue, if all criteria defined by the law are met. The applicant must specify a valid reason (collecting, hunting or sports shooting), have no criminal background and attend a gun-basics course.

While hunting in Germany, if a semi-automatic firearm is used, the magazine must be blocked to accept no more than two rounds of ammunition, meaning that when hunting game animals only three shots in total can be fired (as one additional round is loaded in the chamber) without reloading. This rule is stated in German hunting law and not in German gun law, and does not apply to handguns. Also, it is not allowed to use a magazine that is capable of accepting more than 10 rounds of ammunition while sports shooting in Germany; however, ownership of a magazine that can accept more than two rounds (for hunters) or ten rounds (for sports shooters) is legal in Germany without a license.

The acquisition and possession of ammunition requires a license in Germany, which is usually given with the gun license itself. When purchasing ammunition at a shooting range for immediate use, no license is required.

France

In France, any semi-automatic firearms using military calibers (9mm, 5.56 NATO, 7.62×39, 7.62 NATO, .45 ACP, .50 BMG, .50 AE.) are authorized as 'B category' weapons. While fully automatic 'A category' weapons are highly restricted, semi-automatic ones are legal for civilian possession. A hunting or sports shooting license is required to possess and purchase any firearm, as well as ammunition, in France.

Republic of Ireland

In the Republic of Ireland, legal possession of a semi-automatic AR-15 requires a restricted firearms licence from the applicant's local Garda chief superintendent, who has wide discretion to approve or deny the license. Semi-automatic centrefire rifles are generally may-issue items and the requirements to own one can vary greatly from province to province. Upgraded security measures may be a pre-condition of granting this licence.^[37]

Italy

In Italy, the AR-15 rifle belongs to B7 class and can be owned by civilians, provided it is incapable of fully automatic fire. Like every other gun, it must be registered and to purchase it citizens must have a valid license, which is granted to every person who qualifies.

The rifles are chambered in .223 or 5.56×45 (M193 ball). NATO ammo in 5.56 mm is illegal for civilian use. Due to the Italian legal catalog of rifles, an AR-15 can be considered for hunting use or sports use. If the rifle is classified for hunting use, it is legal to own any number of AR-15s. If the rifle is classified for sporting use, it is possible to own only 6 guns with the same "sporting" classification.

New Zealand

The AR-15 rifle is treated like any other semi-automatic rifle. They are legal to own by individuals holding a firearms license; however, specific features (folding stock, pistol grip, magazines holding more than 7 rounds, etc.) will require it to be registered as a Military-Style Semi-Automatic (MSSA) requiring an 'E Category' endorsement on their license.

Poland

According to Polish laws on firearms, AR-15s and clones do not have any special status. Any civilian holder of firearm licence can purchase and use one without any restrictions, excluding full auto versions. Stock types, magazine capacity, and barrel length are not regulated, although hunting is allowed only with magazines holding six or fewer rounds.

Russia

Russian laws on weapons treat AR-15 rifles as any other rifle. In general, semi-auto only versions with magazine capacity not exceeding 10 rounds are legal for civilians to own, provided that a special "rifled firearm license" is acquired by that individual.

Sweden

The AR-15, like all other semi-automatic rifles, is legal for individuals who need one for competitive use (IPSC rifle or 3-gun matches). A valid competition license is required, and all weapons are registered with the police. The AR-15 is not allowed for hunting use.

South Africa

The AR-15 like any other semi-automatic long arm in South Africa, is legal for anyone who holds any of the following licenses:

• Licence to possess firearm for dedicated hunting and dedicated sports-shooting
• Licence to possess firearm for business purposes
• Licence to possess restricted firearm for self-defence

While not prohibited, common citizens can only own semi-automatic AR-15s if they are members of a hunting or target club, and possess dedicated sport person or dedicated hunter status granted by organisations accredited by the South African Police Service (SAPS).^[38][39] Other licenses allowing the possession of semi-automatic rifles are only available to people who require their use in the conduct of their business (e.g. security personnel), and citizens who can convincingly prove to the Registrar that non-restricted firearms are not sufficient to provide protection. The latter requires a specific motivation for the need of a restricted firearm for self-defence^[38] and have been granted to rhino farmers.^[40][41][42]

United Kingdom

As with all semi-automatic, centerfire rifles, AR-15s are classed as a Section 5 weapon (Prohibited), i.e., a person must provide an exceptional reason and gain permission from the Home Secretary, making ownership all but impossible for a private citizen. However, centerfire AR-15s in a manually operated straight pull configuration or semi-automatic AR-15s that are chambered to fire a .22 rimfire cartridge are legal and can be held on a standard Section 1 Firearms Certificate. There are no restrictions on assault weapon features in the UK, and no restrictions on magazine capacity. There are a number of UK manufacturers of "straight-pull" AR-15 variants. Southern Gun Company has tried to introduce a 9mm "self-ejecting" variant for gallery rifle shooting nicknamed the "Unicorn" but, despite numerous units being sold on the understanding that the rifle was a compliant Section 1 firearm, the rifles were seized and subjected to stringent testing by the UK Forensic Science Service (FSS). A small number of pre-production models were found to be non-compliant with section 1 status. However, later models were deemed Section 1 compliant and were returned to their owners.

United States

At the federal level, AR-15s are legal and considered the same as any other rifle.

During the period 1994–2004, variants with certain features such as collapsible stocks, flash suppressors, and bayonet lugs were prohibited for sales to civilians by the Violent Crime Control and Law Enforcement Act of 1994, with the included Federal Assault Weapons Ban. Included in this was a restriction on the pistol grip that protrudes beneath the stock, which was considered an accessory feature under the ban and was also subject to restrictions. Some rifles were manufactured with a grip not described under the Ban installed in its place. Those AR-15s that were manufactured with the restricted features, as well as the accompanying full capacity magazines, were stamped "Restricted Military/Government/Law Enforcement/Export Only". The restrictions only applied to guns manufactured after the ban took effect. It was legal to own, sell, or buy any gun built before 1994. Hundreds of thousands of pre-ban ARs were sold during the ban as well as new guns redesigned to be legal.

Since the expiration of the Federal AWB in September 2004,^[43] these features became legal in most states.^[44] Also, the manufacture and sale of formerly-restricted rifles has resumed.

Six states, Massachusetts, New York, New Jersey, California, Maryland, and Connecticut, heavily regulate possession of AR-15 type rifles either by the restriction of certain features or outright bans of certain manufacturers' models. California residents may own certain AR-15 type rifles, but they are required to have a fixed magazine not exceeding 10 rounds. Massachusetts and New Jersey have essentially continued following the 1994 Assault Weapons Ban criteria on numerous semiautomatic rifles. New York, Maryland, and Connecticut enacted a ban on sales of AR-15 (and other types of firearms) in response to the December 2012 Sandy Hook Elementary School shooting Massacre. These various state laws have been heavily criticized by many pro-gun organizations.

Under U.S. firearms laws, the lower receiver of the AR-15 is considered a firearm and is subject to purchasing restrictions. The AR-15 upper receiver assembly is considered a part, and may be purchased and mail-ordered in most locations. This is a desirable feature for enthusiasts, who can purchase a number of upper receivers (often in different calibers and barrel lengths) and interchange them with the same lower receiver.

Adding a shoulder stock to an AR-15 with a barrel shorter than 16" would constitute constructing a Short-Barreled Rifle (SBR) under NFA rules, and thus is subject to a $200 tax stamp. The receiver, or serial-numbered part, is still considered a firearm, but a receiver has unique status assigned by the Gun Control Act of 1968 as amended, and by ATF regulations or rulings. ATF ruling 07-07-2009 illustrates a receiver's unique legal status even if the receiver can only be made into a rifle.^[45] Under the United States v. Thompson-Center Arms Company Supreme Court ruling, an individual can possess parts for both the rifle and pistol so long as they are not assembled improperly.^[46] This ruling has been further clarified by the ATF Director in a ruling (ATF Ruling 2011-4^[47]) dated July 25, 2011 which restates most of the findings in the Thompson case.

Following the 1992 ruling, the ATF claimed that the finding in United States v. Thompson-Center Arms Company only applies to products of Thompson Contender, and not to any other companies' products.^[48] This has changed under ATF ruling 2011–4, which states

A firearm, as defined by the National Firearms Act (NFA), 26 U.S.C. 5845(a)(3), is made when unassembled parts are placed in close proximity in such a way that they: (a) serve no useful purpose other than to make a rifle having a barrel or barrels of less than 16 inches in length; or (b) convert a complete weapon into such an NFA firearm.^[49] A firearm, as defined by 26 U.S.C. 5845(a)(3) and (a)(4), is not made when parts within a kit that were originally designed to be configured as both a pistol and a rifle are assembled or re-assembled in a configuration not regulated under the NFA (e.g., as a pistol, or a rifle with a barrel or barrels of 16 inches or more in length).^[49] A firearm, as defined by 26 U.S.C. 5845(a)(3) and (a)(4), is not made when a pistol is attached to a part or parts designed to convert the pistol into a rifle with a barrel or barrels of 16 inches or more in length, and the parts are later unassembled in a configuration not regulated under the NFA (e.g., as a pistol).^[49] A firearm, as defined by 26 U.S.C. 5845(a)(4), is made when a handgun or other weapon with an overall length of less than 26 inches, or a barrel or barrels of less than 16 inches in length, is assembled or produced from a weapon originally assembled or produced only as a rifle.^[49] Such a weapon would not be a "pistol" because the weapon was not originally designed, made, and intended to fire a projectile by one hand.

Furthermore, adding a forward pistol grip to an AR-15 designated as a pistol constitutes manufacture of an AOW (any other weapon).^[50] Both of these actions require an approved "Form 1" and payment of a $200 tax prior to the actual construction of the item. Current wait times for approval average 5–8 months, during which time no modifications or construction may be done.

AR-15 Olympic Arms K8MAG 243 WSSM

As of 2012, there are an estimated 2.5-3.7 million rifles from the AR-15 family in civilian use in the United States.^[51] They are favored for target shooting, hunting, and personal protection, and have become the most popular rifle in America.^[52]

Individual states

California

The Roberti-Roos Assault Weapons Control Act of 1989 banned Colt AR-15 rifles by name in the State of California. California's assault weapons ban following the Supreme Court of California's 2000 decision in Kasler v. Lockyer went further and banned AR-15s made by other manufacturers by name.^[53] AR-15-style rifles that are not named specifically by the Roberti-Roos or other restricted lists can be purchased in the state with some major modifications. Since these are not on the various lists of prohibited firearms, their lower receivers (the part that is legally the firearm) are referred to as "Off List Lowers"(OLL). These OLLs are very common in California, and at least several hundred thousand of them have been sold in the state since the ban went into effect.

Malfunction

With the plethora of manufacturers of complete weapons and aftermarket barrels, there is a potential hazard associated with chamber specifications. Both civilian (SAAMI) specification .223 Remington and 5.56mm NATO are available. Though the external dimensions of the two cases are the same and both chambers typically accept both types of ammunition, the firing of military specification ammunition in civilian specification chambers can produce chamber pressures greater than the barrel is designed to handle. Internally the 5.56×45mm case wall is identical to the .223, though the NATO round is typically loaded to produce higher pressure than the .223. The most common malfunction resulting from firing military 5.56×45mm ammunition in a .223 Remington chamber is that the primer can be forced out of the case by chamber pressure, often resulting in the primer becoming lodged somewhere in the action of the rifle. Disassembly of the rifle is often necessary to remove the jammed primer.^[54]

A few AR-15 manufacturers incorporate the use of a hybrid chamber specification known as the Wylde chamber. Designed by and named after Bill Wylde of Greenup, Illinois, this chambering was designed to accurately shoot the military ball ammo of the day while still feeding reliably. Coincidentally, it shoots the longer 80 gr bullets commonly used in the sport of Highpower Rifle Competition very well and is one of the preferred chambers for that use. While the Wylde chamber allows for optimal seating depth of 80 grain bullets over .223 Remington and 5.56 NATO, it is capable of accepting both ammunition types. The Wylde chamber is used by many manufacturers who sell "National Match" configuration AR-15 rifle, barrels, and upper receivers. The type of chamber, manufacturer, and rifling twist in inches is typically found stamped into the barrel in front of the front sight assembly.

An additional point of concern in the design is the inertial firing pin. A lightweight firing pin rides in a channel inside the bolt unrestrained. When the bolt locks forward during loading, the firing pin typically rides forward and impacts the primer of the chambered round. In military specification ammunition and quality civilian ammunition, this is not normally enough to fire the round and only leaves a small "ding" on the primer. With more sensitive primers or improperly seated primers, this can cause a slamfire during loading.^[55] Another type of malfunction, hammer follow, is also a potential problem for AR weapons systems.

AR-15 and variant manufacturers

Calibers

Pistol cartridges

Metric

Imperial

Rifle cartridges

Metric

Imperial

Shotgun shells

• .410 bore

In addition, the AR-15 lower receiver can be used as a trigger mechanism for single shot or side-fed upper receivers for a variety of larger calibers, including .50 BMG and crossbow bolts.

See also

References

Bibliography

External links

Wikimedia Commons has media related to AR-15.

• Modern Firearms article

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