The 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 their Dual-Feed technology at operator discretion, permitting unprecedented firepower and weapon flexibility.