This Advanced Armament Corp. AR-15 Upper Receiver Assembly in 300 AAC Blackout is a pin-on, ready-to-shoot top end for use with any standard AR-15 lower receiver. The Mil-Spec 4150 chrome moly vanadium steel barrel comes equipped with 1 in 7" twist rifling, M4 feed ramps, a low profile steel gas block, and is finished inside and out with a protective black nitride treatment for superior durability and corrosion resistance. The muzzle is threaded with a 5/8"-24 pitch for easy installation of a silencer, and is topped off with an effective AAC 51T Blackout flash hider.
The upper features a forged M4-Style flat-top receiver onto which a Knight's Armament free floating URX 3.1 Quad Rail System is rigidly attached. The heat-treated, full auto bolt carrier is finished in a slick Nickel Boron coating, and comes equipped with a properly-staked gas key and Carpenter 158 steel bolt assembly.
This 16" 300 Blackout upper utilizes the versatile carbine length gas system, a good choice for this cartridge if various weights and types of ammunition are to be used. Most subsonic and supersonic loads, fired from either a suppressed or unsuppressed gun, are compatible with this configuration. However, some subsonic ammunition may not always cycle reliably under adverse conditions or in a severely fouled firearm without a sound suppressor attached to provide extra backpressure.
Specifications: •Upper Receiver: A3 Flat-Top •Barrel Length: 16" •Barrel Contour: Medium •Barrel Material: 4150 Chrome Moly Vanadium Steel •Muzzle Thread Pattern: 5/8"-24 •Chrome Lined: No •Barrel Finish: Black Nitride / Melonite •Twist Rate: 1 in 7" •Chamber: 300 AAC Blackout •M4 Feed Ramps: Yes •Bolt Carrier: Mil-Spec, Nickel Boron Finish •Muzzle Device: AAC 51-T Blackout Flash Hider •Gas System Length: Carbine •Gas Block Diameter: 0.750" •Handguard: Knight's Armament URX 3.1 Quad Rail, Free Float •Sights: None •Suitable for use with Subsonic or Supersonic loads, either Suppressed or Unsuppressed •Compatible with all standard AR-15 magazines, including Magpul Pmags (Not Included) •5.32 lbs