BG Upper Build Kit 16" 5.56 - Black | A2 | 12" M-LOK | With BCG & CH This build kit DOES NOT come assembled. This Complete 16 inch M-LOK upper receiver build kit comes with a 12 inch free float handguard and includes only the best Mil-Spec components for your AR15 build. The core components of this kit are a barrel that’s machined from chrome moly vanadium 4150 steel, an M4 upper that is machined from 7075 T6 forgings, and our black nitride bolt carrier group that is finished with an incredible polish, making the action smooth and easy to keep clean.As a “do it yourselfers" or DIY enthusiast, you may prefer an AR-15 build kit over a complete upper. Building an AR-15 from a kit allows for a greater level of customization and personalization of the final product. DIYers can choose from a variety of components, such as barrels, handguards, and triggers, to create a rifle that meets their specific needs and preferences. Additionally, building an AR-15 from a kit can be a rewarding and educational experience, as it allows you to gain a deeper understanding of how their firearm functions and how to properly maintain it. Building an AR-15 from a kit may often be more cost-effective than purchasing a complete upper, as it allows DIYers to select only the components they need, rather than paying for pre-assembled parts they may not want or need.We also carry this Upper Receiver Kit assembled here. Barrel: LENGTH - 16" MATERIAL - 4150 CHROME MOLY VANADIUM 11-DEGREE TARGET CROWN - FURTHER IMPROVE ACCURACY PROFILE - M4 FINISH - QPQ CORROSION RESISTANT GAS SYSTEM LENGTH - CARBINE GAS BLOCK JOURNAL - .750" GAS BLOCK JOURNAL TWIST RATE - 1/7 TWIST MUZZLE - 1/2X28 THREADED WEIGHT - 28OZ Bolt Carrier Group: Enhanced 9310 Steel (Bolt) 8620 Tool Steel (Carrier) Bolt is shot Peened and MPI All BCG components are pre-polished before being processed and then post polished for an incredible shine Upper Receiver: Machined from a Mil-Spec 7075 T6 forging Hard Coat Anodized per Mil-A-8625F, Type III M4 Feed ramps Made in the U.S.A. Handguard: 12" free float handguard MIL-STD 1913 Picatinny rail on top 3 M-Lok slots on 3 sides Precision Machined 6000 Series aluminum, for high strength and weight savings Hard Coat Anodized per Mil-A-8625F, Type III, Class 2 Clamp on system for easy assembly Steel Barrel nut to resist movement under heat 11.7 oz with barrel nut and hardware 1.35" Inside Diameter 1.63" Wide Made in USA Charging Handle: Tried and True Standard Charging Handle Forged 7075 Aluminum construction Mil-Spec Type-III Hardcoat Anodized finish Caliber - .223 / 5.56 / 300 Blackout Made in the USA SKU: UBK-BG1655612-BLK UPC: