This article is an excerpt from the Gun Digest Book of Classic Combat Rifles.
IN MARCH OF 1965, the first U.S. troops landed in Vietnam. They were carrying the M14 rifle, chambered for the 7.62×51mm NATO (M80 Ball) cartridge, which had a detachable 20-round magazine and was capable of semi- and full-automatic fire. The military soon learned the M14 on full auto was extremely difficult to control; most burst fire was ineffective.
As a result, many M14 rifles were issued with the selector levers removed, making the rifle effectively, an M1 Garand with a 20-round magazine. The M14 was accurate but heavy, weighing nearly nine pounds, empty. As U.S. involvement in the Vietnam War escalated, our troops encountered North Vietnamese as well as the Vietcong carrying the Soviet-designed AK47 (Avtomat Kalashnikova model 47), chambered for the 7.62×39mm Soviet cartridge, and had a 30-round magazine. The AK’s light recoil permitted controllable, accurate full-auto bursts and American troops began to feel outgunned. The United States needed it’s own assault rifle — and needed it fast.
During the early 1950s, ArmaLite, a division of Fairchild Engine and Airplane Corporation of Hollywood, California, was working on a new assault rifle. The chief engineer was Eugene M. Stoner (1922–1997), described by many as the most gifted firearms designer since John Browning. His first attempt to create a new assault rifle was designated the AR10 (ArmaLite Rifle model 10).
The AR-10 was the first weapon to incorporate Gene Stoner’s patented (U.S. Patent No. 2,951,424) gas system. This system uses a port in the barrel to bleed gas from the fired cartridge into a tube that runs under the hand-guard, from the front sight assembly to the upper receiver and into the carrier key on the bolt carrier.
The pressure gives a hammer-like blow to the bolt carrier, pushing it rearward while simultaneously unlocking the eight-lug bolt from the barrel extension. The bolt and bolt carrier, continuing to move rearward, extract and eject the spent cartridge case and the buffer and recoil/buffer spring return the bolt assembly forward, stripping a cartridge off the magazine, chambering it and locking the bolt into the barrel extension. Using expertise gained in the aircraft industry, Stoner designed the upper and lower receivers of the AR-10 to be made of lightweight aircraft aluminum.
The first AR-10 prototype, chambered for the 7.62×5 1mm NATO cartridge carried in a 20-round magazine, was completed in 1955. The rifle proved extremely accurate for a gas-operated weapon. In December 1955, the first AR10 was presented to the Infantry Board and School at Fort Benning, Georgia, by Gene Stoner and George Sullivan, an ArmaLite executive. Stoner demonstrated his new weapon concept to General William Wyman at Fort Benning on May 6th, just five days after the announcement of the adoption of the M14.
Subsequently, the Board recommended further investigation into the AR-10. In 1957 General Wyman, impressed by the merits and performance of the AR-10, went to the ArmaLite Company and asked Gene Stoner to join a weapons program, offering ArmaLite financial support for future development of ArmaLite rifles in exchange for proprietary rights to the final product. Subsequently, ArmaLite introduced a totally new concept for the modern battlefield, a 22-caliber battle rifle. As a result, the 30-caliber AR-10 was to have a short history with the U.S. military.
The AR-10, scaled down to fire the popular 222 Remington cartridge, had little recoil in semi-auto mode and was amazingly controllable on full-auto. There was heavy resistance to the radical new design from the Ordnance Corps, especially from Dr. Frederick Carten. Doctor Carten was adamantly opposed to weapons developed by commercial companies outside the Ordnance Corps and Springfield Armory, as well as guns made of aluminum and plastic.
General Wyman ordered 10 of these new rifles, along m with 100,000 rounds of ammunition, for Infantry M Board trials. ArmaLite’s W focus was thus changed to the 22-caliber rifle and the AR-15 M (ArmaLite Rifle model 15) was born. In 1958, General Wyman ordered the Army to conduct the first tests on the new AR-15.