THE SECOND CENERATION AR~(57)

摘要

Introduced around 2010, the AR57 blowback upper receiver for the AR15 uses 50-shot P90 magazines and ejects spent casings down through the nominal magazine well for ambidextrous operation. Operating by simple blowback, this upper is available in 6-inch pistol and 16-inch rifle versions. Chambered in 5.7x28mm, this upper is less powerful than the standard 5.56mm version, but that reduction in power brings certain advantages: reduced muzzle blast, a high practical rate of fire, nonexistent recoil, lightness even when fully loaded and, thanks to the top-mounted magazine, the opportunity for the shooter to get very low to the ground for cover. The upper arrives with a custom buffer that fits any carbine AR15 lower.