removed altogether. The black-painted wooden handles are attached to a steel rod via roll pin. With a few exceptions, all the barrels used in the Stoner 63/63A have a six-groove right-hand rifling with a twist rate of 1:12-inch (305 mm), designed to stabilize the lightweight 55-grain M193 projectile, which was standard at the time. At the Army's request, Cadillac Gage submitted for testing rifles, carbines, and light machine guns, with 1:9-inch (230 mm) twist barrels, respectively designated XM22E2, XM23E2, and XM207E2. The different twist was to test the 68-grain XM287 and XM288 bullets. After NWM obtained a license to produce the Stoner 63A, some barrels were manufactured with a 1:8-inch (200 mm) in rifling pitch to be used with heavier experimental bullets. None of these were ever produced in significant numbers. Fire control The Stoner 63/63A LMG is an automatic weapon that fires from the open bolt and the trigger mechanism permits only fully automatic firing. The entire trigger unit has four trigger pins that give the unit its modularity. The front pin holds a flapper-type magazine catch/release (used in the Rifle/Carbine variants and the left-hand feed LMG with a 150-round drum-type belt container), a full dust cover (used with the top-feeding Automatic Rifle or vertically mounted ammo box on any belt-fed system) or a half size dust cover (used with the right-hand-feed bottom box carrier). The next two pins retain the timer and hammer, both of which are absent in the open bolt configurations. The final pin acts as the trigger's axis shaft; the spring-loaded sear pivots on the selector lever's axis pin. The selector is disconnected when firing from the open bolt and a sliding manual safety installed near the trigger guard disables the trigger when pushed to the rear. The rear portion of the trigger housing serves as a receiver end cap and is used to attach the shoulder stock. The black polycarbonate pistol grip is also attached to the trigger housing. The checkered grip is flared at the bottom to prevent the shooter's hand from sliding off and has an internal storage compartment sealed by a hinged cover with a spring-loaded hatch. Features The hooked, non-reciprocating steel charging handle is typically mounted on the right side of the receiver. It has 24 lightening holes and engages a projection on the piston to draw the piston and bolt group to the rear (cocked) position. The handle should