Aero Precision M4E1-E 13.9in 5.56x45mm NATO EM12.7 Complete Upper Receiver

Aero Precision M4E1-E 13.9in 5.56x45 NATO EM12.7 Complete Upper Receiver. This complete upper includes Aero Precision Atlas S-One Handguard and assembles with a slim, lightweight profile. Key specifications include a 13.9 in CMV barrel, mid-length gas system, 1/2x28 threads, and an A2 flash hider. Includes M4E1 threaded assembled upper receiver and a full upper assembly ready to drop into mil-spec AR-15 receivers. Features M4E1 threaded receiver with enhanced forging, A2 flash hider, M4 feedramps, .250 takedown pin holes, laser-engraved T-marks, port door and forward assist installed, Atlas S-One handguard with front and rear Picatinny rails, weight-reducing center rail removal, 12:00 indexing grooves for grip control, QD sockets at 3, 6, and 9 o'clock, and compatibility with low profile gas blocks. Handguard is 12.7 in and designed for MIL-SPEC AR-15 upper receivers and barrels. Barrel: 13.9 in, Mid-Length, 5.56 NATO, 1-7 twist, 1/2x28 threads, CMV 4150 steel. Gas system: Mid-Length. Includes low-profile gas block and pistol-length gas tube. Country of origin: USA.