All our uppers are carefully assembled and tested and ready to go out of the box. Every component is chosen to ensure a high quality upper is produced. Every upper is custom built to order and we go the extra mile to ensure the finished product is to your specifications. This 45 ACP upper starts with an AR-15/AR-45 MILSPEC 7075 T6 Billet Aluminum receiver, mated to a Hitman Industries 16.5 inch 45 ACP, 1:16 Twist, Nitride/Melonite treated barrel. Hitman is one of our major partners in the industry and they especially make great pistol caliber barrels. The Axis Rail is a free floated system, M-LOK slots on all three sides, full length picatinny rail at the top, lightweight handguard. Barrel Nut is made out of solid steel to ensure a solid mounting system. Bolt Carrier Group and Charging Handle is OPTIONAL. We offer a 45 ACP BCG, Full Auto Profile, Properly Heat Treated, 8620 Single Piece Bolt, Nitrided and a Standard Charging Handle. Also an OPTION is COLOR. We can change the receiver and handguard to FDE (FLAT DARK EARTH) COLOR (see pictures).. SPECIFICATIONS UPPER RECEIVER: AR-15/AR-45 Mil-Spec Machined out of Billet Aluminum, Type III Hardcoat Anodized Black - No Forward Assist and Ejection Port Cover Needed BARREL: 16.5 inch, 45 ACP Caliber, 4150 Chrome Moly Vanadium Steel, 1:16 Twist, Nitride/Melonite Treated - made by Hitman Industries HANDGUARD: 12 inch M-LOK Free Floated, Machined out of 6061 T6 Aluminum - made by Axis MFG GAS SYSTEM: Blowback System GAS BLOCK: Blowback System - No Gas Block Needed MUZZLE DEVICE: Standard A2 (Enlarged to 45 Cal) Flash Hider and Crush Washer 100% MADE IN THE USA OPTIONAL: ADD a P2A 45ACP Nitride BCG and a Standard Charging Handle OPTIONAL COLOR Change to an Aero Precision XL FDE Colored Receiver and 12 inch M-LOK Magpul FDE Colored Handguard