Spike's Tactical 5.56 NATO M16-profile bolt carrier group with full nickel boron (NiB) coating inside and out - a USA-made, mil-spec-grade BCG built for shooters who run their AR-15s hard and want fast cleanup. The NiB coating reduces friction across the bolt, carrier, and gas key, which translates to smoother cycling, less lube dependence, and powder fouling that wipes off with a rag instead of a brush. The carrier is shot-peened and properly staked at the gas key, and the bolt is fully magnetic-particle inspected and high-pressure tested. The unmistakable laser-engraved ST Spider logo on the side of the carrier marks the part as a genuine Spike's component. Caliber: 5.56 NATO / .223 / .300 BLK Carrier profile: Full-mass M16 Finish: Nickel Boron coating inside and out (bolt, carrier, and gas key) Markings: Laser-engraved ST Spider logo Inspection: MPI bolt, HPT, gas key staked Origin: USA Run wet for the first 200 rounds even though NiB tolerates dry running well - it lets the bolt and carrier seat against the upper receiver and chamber face before sustained fire. Inspect bolt-ring gaps and gas-key staking before first range trip.