effort to increase profits from the ArmaLite venture, Fairchild decided to compete in the U.S. Army's CONARC requirement for a new six-pound, high-velocity, .22-caliber selective-fire rifle accurate to 500 yards. In response, ArmaLite engineers Gene Stoner, Jim Sullivan, and Bob Fremont used the basic AR-10 design to produce the ArmaLite AR-15 in .223 Remington, which was completed as a firing prototype in 1958. Fairchild-ArmaLite continued its efforts to sell both the AR-10 and AR-15 to various military forces around the world. However, the AR-10 rifle marketed by ArmaLite after 1958 was not the product-improved AR-10 developed by Artillerie Inrichtingen, but rather a design scaled-up from AR-15 plans and specifications, the AR-10A. None of the improvements incorporated by Artillerie Inrichtingen over three years of production were used in the new AR-10A. Although the AR-10A did not benefit from the modifications undertaken by the Dutch licensee, it had some differences from the AR-15 (besides caliber and part dimensions), including a different bolt, trigger, and cocking handle design, along with a magazine canted forward at a five-degree angle. While interest in the AR-15 was considerable, the AR-10A failed to attract any orders from domestic or foreign military customers. In 1959, ArmaLite sold its rights to the AR-10 and AR-15 to Colt Firearms due to financial difficulties, and limitations in terms of manpower and production capacity. After modifications (most notably, the charging handle was re-located from under the carrying handle like AR-10 to the rear of the receiver), the new redesigned rifle was subsequently adopted by the U.S. military as the M16 Rifle. Colt continued to use the AR-15 trademark for its line of semi-automatic rifles marketed to civilian and law-enforcement customers, known as Colt AR-15. Design details The AR-10 is a lightweight, air-cooled, magazine-fed, gas-operated rifle that uses a piston within the bolt carrier with a rotary bolt locking mechanism. The rifle has a conventional layout; it features an in-line stock, an aluminum alloy receiver and a fiberglass reinforced pistol grip, handguard, and buttstock. As part of the weight-saving design philosophy, in the designer points out that: ″By having the bolt carrier act as a movable cylinder and the bolt act as a stationary piston, the need for a conventional gas cylinder, piston and actuating rod assembly is eliminated.″ While mostly an original design, the AR-10 built upon previously proven concepts. From the FAL it took the hinged receiver system allowing the rifle