WMD Guns Bolt Carrier Group, Without Hammer, NiB-X Finish NIBXBCG-0001 BCG components are NiB-X coated and polished to reduce fouling adherence. Coating is guaranteed for life against chipping" spalling or flaking. Over 30K rounds in Government protocol endurance testing did not wear the coating off. Especially beneficial in short barrel setups and suppressed platforms.