ArmaLite AR-15

The AR-15 is a magazine fed center rifle from the Armalite Corporation. It is light-weight and auto loading. It is available in automatic and semi-automatic variants. The AR-15 was designed by Eugene Stoner as a smaller caliber version of the AR-10. Armalite sold its right on the AR-15 in 1969 to Colt.

The rifle has a .223 Remington, 5.56 x 45 mm NATO caliber. It measures 991 mm. (39 in) in length and has a mass of 7.5 lb (3.4 kg.). The barrel stands at 508 mm (20 in) in standard and 406 mm (16 in) or 368 mm (14.5 in) in common.

The earlier models of the AR-15 had 1:14 rate of twist, while the newer configuration offers a 1:12, 1:9 and 1:7 rate of twist. Standard issue magazines are 20 to 30 double rack stack magazines, with drum rounds of 90 to 100 round capacities also available. Some low capacity magazines are also available to comply with legal restrictions in specific areas.

The AR-15 had the designs of many other successful guns imbibed in it. It had the successful locking system of the Johnson Automatic Rifle. The gas system was from the Swedish Ljungman AG42B, and the hinged upper/lower from FN-FAL. The rear sights in carry handle like British EM2 and finally the ejector port cover from MP44

The AR-15 was revolutionary in the gun industry when it first hit the markets. It had a modular design which made it easily repairable and allowed a variety of accessories to be added to the rifle. Upper receivers which incorporate barrels of varying lengths and weights are available for this rifle. Therefore, the rifle can handle different caliber ammunition easily. The rifle had a small caliber but high velocity round. It was one of the first rifles to have synthetic grips and stock which prevented any warping or splintering.

The mechanism of operation for the AR-15 is known as gas impingement. The rifle has a gas port located under its front sight base. The bullet moves past this gas port while the gas is taken from the barrel. The gas then barges into the port and travels down a gas tube located above the barrel. A gas key accepts the gas and funnels it into the bolt carrier. This forces the gas to expand inside the bolt carrier and therefore forces the bolt and the carrier to move in opposite directions.

The bolt turns and unlocks from the barrel extension as the bolt carrier moves towards the butt of the gun. The cam pin makes the bolt rotate and follow a groove cut into the carrier. This twists and allows the bolt to unlock. After the bolt is unlocked, the chamber moves backwards and towards the butt of the gun. It is then that the chambered casing is extracted.

The bolt carrier is pushed back towards the chamber by a return spring located behind a buffer. The groove in the upper receiver traps the cam pin and doesn't allow it and the bolt from closing. The locking of the bolt lugs pushes a fresh round up the feed ramps and into the chamber.

When the bolts locking lugs move past the receiver extension, the cam pin twists into the pocket in the upper receiver. This action follows the groove in the carrier and allows the bolt to twist and lock into the barrel's extension.

The front and rear ironsight were especially advantageous to the user. While the front ironsight was adjustable for elevation, the rear ironsight was adjustable for windage and distance. Along with this, the AR-15 had a large number of optical devices which could be used in place of the ironsights.

Due to the low cost, modularity and accuracy of the AR-15, it was adapted by the US Army under the name M16. The AR-15 has captured the imagination of sports shooters as well as the legal system too.

The AR-15 is manufactured and sold by many companies today. Therefore, various customized versions of the AR-15 have become available in the market. A wide range of configurations are available today. Short carbine length models, with features like adjustable length stocks and optical sights are available, as are the heavier barrel models.

The rifle has always been in the news ever since it was first released. Due the Violent Crime Control and Law Enforcement Act of 1944, some AR-15s with modifications were termed illegal. The Assault Weapons Ban termed these rifles with certain modifications illegal, but since the expiration of the AWB, these rifles and modifications are illegal only in some states.

The state of California has been the most recent to ban the modified AR-15s. However, if one replaced the lower receiver of the rifle with one which can have ten rounds magazine would make it legal and give space for some fantastic customizations.