then be pushed back forward allowing a flat-spring latch riveted to the front end to capture a slotted plate welded to the front of the receiver. With the right-hand feed mechanism with underslung box carrier installed the handle is awkward to operate, so a special slotted forearm with a bottom cocking handle was developed. The nucleus of the Stoner 63 system is the receiver which is a rectangular sheet metal pressing. The gas cylinder, support structures, brackets, lugs and other devices are welded in place. The front portion carries the piston and barrel and is perforated to reduce weight and improve air circulation around the barrel and gas cylinder. The rear segment holds the piston extension and bolt group. The ejection port is on the right side when the receiver is inverted and the weapon is configured as a rifle or carbine and on the left side when in the various machine gun roles. The various components are phosphate finished and then coated with a black baked enamel finish called Endurion. Early examples of the Stoner 63 were delivered with all wood furniture, however these were soon replaced with black polycarbonate parts with the exception of the handguard, which remained wood, but was painted black. The Stoner 63 bipod is a non-locking type that attaches to the gas tube; it does not pivot and has a limited height adjustment feature. The Stoner 63A bipod is extensively perforated with lightening holes and can be locked in either the stowed or deployed positions. It too does not pivot but is compatible with the earlier Stoner 63, whereas the Stoner 63 bipod will not work with the later 63A pattern guns as the gas tube is of a larger diameter. Sights The sight arrangement on the Stoner 63/63A differs amongst the various configurations. On the belt-fed LMGs, the rear sights are mounted on the top cover. These consist of a folding leaf aperture elevation scale graduated in 100 m increments from 200 to 1,000 m. The rear sight can also be corrected for windage in ¼-mil increments. When the primary sight is folded down, a battle sight aperture with a diameter of is exposed. The Rifle and Carbine versions have simple flip-type apertures with settings for 0–300 and 300–500 m contained between large perforated protective ears. The sights are adjustable in both windage and elevation in 1 MOA increments. All variants share the