5.7x28mm Complete Upper 16 - AR57

This complete upper receiver is ready to drop onto your AR-15 lower receiver and convert it into a 5.7x28mm firearm making it an AR-57!This 5.7 upper ships with a 50-round P90 style magazine included that attaches above the barrel allowing the original lower receiver's magazine well to be used as an ejection port.Also included is a 5.7x28mm optimized buffer that suits the lighter recoiling round. The upper's handguard uses MLOK slots along with small 1913 Picatinny rail sections to allow for a