Enhanced upper receiver is everything you need to convert your AR carbine or pistol to the exciting new 300 AAC Blackout (300 BLK) round. Features a nitrided, 1"-8 twist barrel with M4 feed cuts, a Knight’s Armament URX free-floating handguard, and AAC'S 51T flash suppressor. 51T accepts the AAC 762-SDN-6 sound suppressor to make the gun nearly silent when used with subsonic ammunition. The nitride treated bore and chamber provide excellent corrosion resistance and a longer service life than standard chrome-lined barrels, and the full-profile M16 bolt/carrier group allows these uppers to function on a full-auto M16 lower as well as on semi-auto guns. Available with standard 16" or 12.5" Carbine and 9" Pistol barrels, designed to function with subsonic and supersonic ammunition.
AR-15, Issue:09, Page:005
Brownells Christmas , Issue:3X, Page:021
Big Book Catalog, Issue:66, Page:005
Receiver – Aluminum, M4 Feedramps, Picatinny Top Rail, Matte Black Anodizing, M16 Bolt Carrier Group. Handguards –Freefloat URX II (12.5" and 16”) or URX III (9”). Barrel – 16”, 12.5", or 9” nitride 300 Blackout, 5/8-24 threaded muzzle, 51T Blackout Flash Hider.
The 9" AAC 300BLK Uppers are designed for use with a carbine receiver extension, standard GI Buffer Spring, and an H2 Buffer.
The 12.5" and 16" AAC 300BLK Upper is designed for use with a carbine receiver extension, standard GI Buffer Spring, and a CARBINE Buffer.