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.
SPECS: 7075 T6 aluminum, NiB-X® coating with matte ceramic finish, Black or Flat Dark Earth. Stripped receiver only. Fits standard AR-15/M16 lowers, and accepts standard barrels and upper receiver parts. .250" dia. pivot/takedown pin holes. M4 feed ramps.
NiB-X~ Upper Receiver, Black