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 300 Blackout upper kit starts with an AR-15 MILSPEC 7075 T6 Forged Aluminum receiver, mated to a Tactical Kinetics 7.5 inch 300 Blackout, Pistol Length Gas System, 1:7 Twist, Medium Profile, Nitride/Melonite treated barrel. Tactical Kinetics is one of our major partners and they produce high quality, accurate 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. Comes with the Bolt Carrier Group and Standard Charging Handle. Also included is a lower parts kit and stabilizing fin/blade kit to turn your stripped lower receiver into a full pistol or rifle. This configuration has an extended handguard longer than the barrel, with a flash can to provide a sleek look and maximum sight radius. SB Tactical SBA3 Adjustable Brace is OPTIONAL. Features a minimalist design, integral and ambidextrous QD Sling socket and capable of accepting milspec carbine buffer tube extensions. We can also UPGRADE the GAS BLOCK to an Adjustable Gas Block. Great option if you are using a suppressor or just want to fine tune your system. Also an OPTION is COLOR. We can change the receiver and handguard to MAGPUL FDE (FLAT DARK EARTH) COLOR (see pictures). SPECIFICATIONS UPPER RECEIVER: AR-15 Mil-Spec Machined out of 7075-T6 Forged Aluminum, M4 Feed Ramps, Type III Hardcoat Anodized Black with Forward Assist and Ejection Port Cover Installed BARREL: 7.5 inch, 300 Blackout Caliber, 4150 Chrome Moly Vanadium Steel, 1:7 Twist, Medium Profile, Nitride/Melonite Treated - made by Tactical Kinetics HANDGUARD: 9 inch M-LOK Free Floated, Machined out of 6061 T6 Aluminum - made by Axis MFG GAS SYSTEM: Pistol Length, Direct Impingement, Stainless Steel Tube GAS BLOCK: Low Profile Gas Block, Machined out of 4140 Steel MUZZLE DEVICE: Kak Industry Slimline Flash Can BOLT CARRIER GROUP: 300 Blackout Caliber, M16 Profile, Mil-Spec, MP Tested, Nitride Treated, Properly Staked Gas Key, 8620 Steel Carrier, 9310 Steel Bolt CHARGING HANDLE: Standard Charging Handle LOWER PARTS: UNBRANDED AR ELG Lower Parts Kit BLADE/BRACE: AR-15 Stabilizing Fin/Blade Kit - includes stabilizing fin/blade, standard buffer spring, 3oz buffer, castle nut, latch plate and pistol buffer tube. 100% MADE IN THE USA OPTIONAL: UPGRADE BLADE to a SB Tactical SBA3 Adjustable Brace OPTIONAL: UPGRADE GAS BLOCK to an Adjustable Gas Block OPTIONAL: COLOR Change to a Magpul FDE Colored Receiver and 10 inch M-LOK Magpul FDE Colored Handguard