Nib-X® Upper Receiver, Black

Ultra-Hard, Smooth-As-Glass Finish For Maximum Durability & Smooth Cycling

Stripped receiver has WMD’s NiB-X nickel boron coating inside and out to provide an exceptionally tough, ultra-smooth surface finish for outstanding wear resistance and lubricity. A ceramic topcoat is applied for color on the exterior only, leaving the nickel boron exposed inside to keep friction with the bolt carrier to the absolute minimum. Works great with standard carriers, too, but even smoother with nickel boron coated bolt carriers, including WMD’s NiB-X coated carrier, available separately. M4 feed ramps ensure reliable feeding.