One of the many notable products of American arms designer Eugene Stoner (of AR10, M16/AR15, and AR-18/180 fame, among others), the genesis of the 63 was in the early 60s, shortly after his departure from Armalite. Working with Cadillac-Gage, Stoner developed a modular weapon system, intended to be capable of a radical degree of customization at the field armorer level, creating a receiver that could be reconfigured rapidly for mission and environment; while a number of modern weapons designs have touched on this sort of flexibility, this was an exceptional capability for the era. Developed with an eye for military sales, the 63/63A was issued on a trial basis in multiple configurations to the United States Marine Corps and select elements of the Navy SEALs and U.S. Army Special Forces operating in Southeast Asia. The system was not adopted for general use; while it had many virtues, and was considerably refined with user feedback, it was more complex and maintenance intensive than the M16 rifle. While development stopped in 1971, the design found fans among America's elite units, especially in the Light Machine Gun configuration; the Stoner LMG gave belt-fed firepower and suppression ability at a significantly lower weight than the standard M60 machine gun, which meshed well with highly mobile small unit tactics. Around 4,000 are believed to have been made in total, many of which were destroyed after the 63A was replaced by the M249 Squad Automatic Weapon. This desirable example is built on a fully transferable Knight's Armament manufactured receiver, marked "STONER 63A CAL. 5.56MM/MFG. BY KNIGHT'S ARMAMENT CO./VERO BEACH, FLA.," of which only a small amount were ever produced. Features a winged post front and adjustable flip-up peep rear sights. A quick-release lever ahead of the feed cover allows rapid detachment of the barrel, fitted with a wood carry handle, with a non-reciprocating charging handle on the underside of the polymer forearm. The trigger group is fitted with a checkered polymer pistol grip and a straight buttstock with a "STONER/63" marked buttplate with an ambidextrous selector switch marked "SEMI" and "AUTO" (fires open bolt full auto in all positions). The feed mechanism is set up in a left-hand configuration, in which rounds feed into the action from the right side.

Excellent overall, retaining 95% plus original black and phosphate finishes, with some light handling marks, cycling wear, and crisp grip checkering. The stock shows a few light scuffs. Mechanically functions well in full automatic only. Transferable Stoner 63A machine guns like this, let alone examples with a KAC receiver, are exceedingly scarce. NOTE: This weapon is a National Firearms Act (NFA), fully transferable Class 3, which is registered with the Bureau of Alcohol, Tobacco, Firearms and Explosives, (BATFE) under the provisions of 18 U.S.C. Chapter 44 and 27 CFR part 479.