One of the many notable products of famed 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's establishment in Costa Mesa, California, 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. The design found fans among America's elite units. While production ended in 1971, the 63 and 63A were retained by the Navy SEALs well into the 1980s, only being fully retired with the adoption of the M249 Squad Automatic Weapon; the bulk of the Stoners still in inventory are believed to have been destroyed. Elevation adjustable post front and two-leaf windage adjustable peep rear sights, with a birdcage flash hider and bayonet lug on the quick-release barrel, ventilated receiver with ribbed handguard, right-handed "SAFE"/"SEMI"/"AUTO" selector, checkered pistol grip and fixed buttstock. The barrel, forearm, buttstock, rear sight base and trigger housing can all be removed without dedicated tools. The top of the receiver bears the model, caliber and manufacturer markings, with "STONER/63" on the buttplate. Included with the lot is a spring-loaded clip-on bipod with telescoping legs.