AR-15
The AR-15 is a lightweight, air-cooled, magazine-fed, autoloading, centerfire rifle. The original Armalite/Colt AR-15 was a selective-fire prototype submitted for consideration as a military infantry rifle, and is distinguished from later civilian-model AR-15 and AR-15A2 rifles marketed by Colt Firearms.
The AR-15 is based on the 7.62mm AR-10, designed by Eugene Stoner of the Fairchild ArmaLite corporation. The AR-15 was developed as a lighter, 5.56mm version of the AR-10. The "AR" in AR-15 comes from the ArmaLite name, not "assault rifle".
ArmaLite sold its rights to the AR-10 and AR-15 to Colt in 1959. Colt marketed the AR-15 rifle to various military services around the world, including the U.S. Air Force, Army, and Marine Corps. The AR-15 was eventually adopted by the United States military under the designation M16. However, Colt continued to use the AR-15 trademark for its semi-automatic variants (AR-15, AR-15A2) marketed to civilian and law-enforcement customers. The original AR-15 was a very lightweight weapon, weighing less than 6 pounds with empty magazine, though later heavy-barrel versions of the civilian AR-15 can weigh upwards of 8.5 lbs.
Today the civilian-model AR-15 and its variations are manufactured by many companies and have captured the affection of sport shooters and police forces around the world due to their low cost, accuracy, and modularity. (Please refer to the M16 for a more complete history of the development and evolution of the AR-15 and derivatives.)
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 manufacturers make AR-15 clones marketed under separate designations, although colloquially, these are sometimes also referred to by the term "AR-15".
Operating Mechanism
The mechanism of operation for the rifle is known as direct gas impingement. Gas is tapped from the barrel as the bullet moves past a gas port located under the rifle's front sight base. The gas rushes into the port and down a gas tube located above the barrel. The gas tube runs from the front site base into the AR-15's upper receiver. Here, the gas tube telescopes over a “gas key” which accepts the gas and funnels it into the bolt carrier. The movement of gas into the bolt carrier forces the bolt and carrier in opposite directions. As the bolt carrier moves towards the butt of the gun, the bolt begins to turn and unlock from the barrel extension. The cam pin is responsible for the bolt's rotation as it follows a groove cut into the carrier that twists and permits the bolt to unlock. Once the bolt is unlocked, the carrier continues to move towards the butt of the gun and the chambered casing is extracted.
A return spring located behind a buffer then pushes the bolt carrier back towards the chamber. A groove machined into the upper receiver traps the cam pin and prevents it and the bolt from rotating into a closed position. The bolt's locking lugs then push a fresh round up the feed ramps and into the chamber. As the bolt's locking lugs move past the receiver extension, the cam pin is allowed to twist into a pocket milled into the upper receiver. This twisting action follows the groove cut into the carrier and permits the bolt to twist and “lock” into the barrel’s extension.
Legal status in the United States
In the United States, variants with certain features such as collapsible stocks, flash suppressors, and bayonet lugs were prohibited for sales to civilians during the period 1994-2004 by the Violent Crime Control and Law Enforcement Act of 1994, under the provision known as the Assault Weapons Ban. Those that were manufactured with those features were stamped, "Restricted Military/Government/Law Enforcement/Export Only" as well as the accompanying high capacity magazines. Since the expiration of the Federal AWB in September of 2004, these features are now illegal only in certain states.
The 2000 Assault Weapons in the state of California sparked a renewed interest in the AR-15 rifle. It is estimated that some 60,000 California Legal AR-15s are in existence in that state.[citation needed] Replacing the Lower Receiver of a standard AR-15 with one that has a fixed (10 round) magazine (see below for instructions) will render the firearm "California legal", and able to utilize banned features such as a telescoping stock and pistol grip. The magazine is not detachable so to load the rifle a shooter must pull the rear takedown pin, hinge the upper receiver on the front takedown pin, and load the now exposed magazine either with a stripper clip or by hand, then close. Popular lower receivers for this purpose are manufactured by Stag Arms, Fulton Armory, Dane Armory, Mega, and Ameetec. Stag makes a lower receiver called the STAG-15 which is considered an "off-list" receiver by the CA DOJ and is legal. As of December 2006, Doublestar, Stag Arms, CMMG, and MEGA all qualify as "off-list" lowers in the state of CA. There is also one model made by Colt, the CAR-A3 HBAR Elite, that was never banned by name and thus still legal to own in California provided it has the correct configuration. This receiver can be made into a full rifle if the following requirements are met: the receiver has a fixed magazine with no more than 10 cartridges - in which case the rifle may have pistol grips, folding or collapsing stocks, etc.; or, the receiver may have a detachable magazine but may NOT possess any sort of attachment such as pistol grips, folding or collapsing stocks, etc.