The Faxon Firearms 5.56 / .223 9310 Bolt is a stripped replacement bolt for an AR-15 bolt carrier group, machined from 9310 tool steel and finished in black nitride. This is the bolt head only - it drops into your existing BCG carrier in place of the factory 8620 mil-spec bolt. The cam pin, firing pin, retaining pin, and carrier are not included. Key features: 9310 tool steel - higher hardness than 8620 mil-spec S7 tool steel extractor for long-cycle durability Nitride finish - lower friction, better corrosion resistance than phosphate Bolt lugs chamfered 45 degrees for reliable feeding even on hot hand loads Fully MPI (magnetic particle inspected) - verified material soundness HP (high-pressure) tested Mil-spec dimensions - fits any standard AR-15 / 5.56 / .223 BCG carrier What you get: 1x Faxon 5.56 / .223 9310 stripped bolt (nitride) Pre-installed extractor + spring Not included: carrier, cam pin, firing pin, retaining pin. Reuse the parts from your existing BCG, or pair this bolt with a separately purchased carrier and small-parts kit if you are building a BCG from scratch. Best for: Replacing a worn or cracked factory bolt without replacing the entire BCG, or upgrading a mil-spec 8620 bolt to a harder 9310 piece for high-round-count training, suppressed builds, or duty rifles.