You can find the Rise Armament Advanced Bolt Carrier Group Nitride .223/5.56 here.

The Rise Armament Advanced Bolt Carrier Group is treated with a high strengh and easy to clean black Nitride finish. The BCG is MPI tested and the extractor is shot peened. The bolt is made from 9310 steel, the carrier is made from 8620 tool steel and heat treated and case hardened. The gas key is made from tool steel and uses grade 8 hardened fasteners that are staked properly.

All Rise Armament products are manufactured according to strict AS9100 and ISO9001 2008 procedures, and must pass stringent QA inspection before leaving the factory.

Caliber: .223/5.56
Finish: Black Nitride