Buy your Aero Precision M4E1 Threaded PRO Complete Upper from BattleHawk Armory today! The Aero Precision M4E1 Threaded PRO Complete Upper is a top-tier upper receiver assembly designed to deliver superior performance and versatility for AR-15 platforms. The heart of this complete upper is the 13.7" cold hammer-forged (CHF) mid-length barrel chambered in 5.56mm NATO. The CHF process ensures excellent durability, accuracy, and heat resistance. The 13.7" length strikes a balance between maneuverability and ballistic performance, making it suitable for various shooting applications. The threaded muzzle allows for easy attachment of muzzle devices such as flash hiders or compensators. The upper receiver itself is the M4E1 enhanced model from Aero Precision. It features a forged 7075-T6 aluminum construction, providing exceptional strength while maintaining a lightweight profile. The M4E1 design incorporates a unique handguard mounting system that securely attaches the 12.7" ATLAS R-ONE handguard to the upper. The ATLAS R-ONE handguard is constructed from 6061-T6 aluminum and offers a slim profile, M-LOK attachment points, and a continuous top rail for easy accessory mounting and customization. Finished in a sleek black anodized coating, the upper receiver not only enhances the aesthetics but also provides corrosion resistance and durability. It is compatible with mil-spec lower receivers and most AR-15 components, offering a wide range of customization options. Overall, the Aero Precision M4E1 Threaded PRO Complete Upper is a premium upper receiver assembly that combines precision engineering, durable construction, and advanced features. It is an excellent choice for shooters seeking enhanced performance, reliability, and customization capabilities for their AR-15 platform. NOTICE: The muzzle device on this upper receiver is not pinned or welded. All NFA rules and regulations apply. DOES NOT INCLUDE BCG OR CHARGING HANDLE Includes: 13.7" PRO 5.56 Cold Hammer Forged Barrel M4E1 Threaded Upper Receiver ATLAS R-ONE Handguard VG6 Delta Flash Hider Mid-Length Gas System About Cold Hammer Forging Cold hammer forging differs from other common barrel manufacturing processes. Rather than drilling a blank and using cutters, buttons, and reamers to machine the chamber and rifling into the barrel, a cold hammer forged barrel is made by forming the barrel around a mandrel that has the rifling inclusions precision ground into it. This process is referred to as "cold" hammer forging because the process is done at room temperature and the metal is not heated.