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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. 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, 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. 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, with Colt's manufacture of their first 300 AR-15s in December 1959.〔p.96 Dockery, Kevin ''Future Weapons'' Berkley Books, 2007〕 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. 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.〔(Blue Book Publications – COLT'S MANUFACTURING COMPANY, LLC AR-15, Pre-Ban, 1963–1989 Mfg. w/Green Label Box ). Store.bluebookinc.com. Retrieved on 2011-09-27.〕 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. 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 is lightweight, highly corrosion-resistant, and machinable. * Modular design 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 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 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 capacity, 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 as a MILSPEC standard 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, but the full automatic M16 bolt carrier is now the most popular type, and approved by ATF. This was 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. In the late 1970s and early 1980s, items such as the "Drop In Auto Sear" or "lightning-link," conversion to full automatic was very straightforward (sometimes requiring machining of the lower receiver with use of a mill and M16 Bolt Carrier Group).〔(【引用サイトリンク】title=Lightning Link Page )〕〔(【引用サイトリンク】title=Drop in Auto-Sear Page )〕 Such modifications, unless using registered and transferable parts made prior to May 19, 1986, are illegal. (The Firearm Owners Protection Act in 1986 has redefined a machine gun to include individual components where 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 such items. 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 functions to rotate between safe and fire. Some other manufacturers may mark their rifles with three-positions for collectors and re-enactors, though the guns will not fire in those modes. However weapons modified to full automatic using a lightning-link are capable of full automatic fire only—unless a special full automatic fire select mechanism and modified selector-switch is substituted.〔 Also many AR-15's made before 1986 were converted to be M16's Via gunsmiths who legally turned them into Form One rifles in the U.S. Ways to Identify the converted AR's is by seeing an Auto Sear in an AR-15 marked lower receiver.〔 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 use by Federal Firearm Licensees for manufacturing/distributing select-fire variants of the AR-15 to Law Enforcement, Military and Overseas customers. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「AR-15」の詳細全文を読む スポンサード リンク
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