Our innovative RAPTOR belt-fed upper receiver assembly is designed to interchange with standard AR/M4 type uppers and readily fits any MIL-Spec lower receiver without permanent modification to the host lower, and is rearward compatible to AR15/M16 models produced as early as 1963. Once installed, the patented RAPTOR upper receiver system allows you to feed from standard box type AR15/M16 magazines or M27 linked ammunition. Spanning the capability range from the optic ready carbine through a lightweight support rifle. The RAPTOR can be user-configured in seconds without tools to adapt to virtually any mission profile. Utilize our Dual-Feed® technology at operator discretion, permitting unprecedented firepower and weapon flexibility.   KEY FEATURESDrop-On Upper Receiver Assembly that upgrades your AR15/M16/M4 type lower receivers or rifles5.56 x 45mm NATO16.25” Self-Regulating Quick- Change Barrel1:7” RHT, ½”-28 TPI, CrMoV NitridedShort-Stroke Gas Piston OperationDual-Feed® - Accepts ALL AR15/M16 Magazines & M27 Linked AmmunitionPrecision Machined 7075-T6 Billet Upper Receiver, Feed Cover and Charging HandlePrecision Machined Billet Steel Feed Tray Finish – Manganese Phosphate & MIL-A8625F Hardcoat anodize - BlackFull-Auto Bolt CarrierHandguard Style – Lightweight Aluminum with MLOK style slots at 12, 6, 10, and 2 o'clock positions.Optic ReadyShips with Main Action Spring, Bolt Catch, Carbine Stock Spacer, (100) M27 Links & Operator’s ManualMade In USA