Faxon Firearms Black Nitride 9310 Bolt, 5.56 NATO AR-15

The Faxon Firearms black nitride bolt (brand part no. FF556BCNITRIDE) is a 5.56 NATO AR-15 bolt built to go beyond mil-spec rather than just meet it. Faxon machines the bolt body from 9310 tool steel and nitrides the entire assembly, which increases surface hardness, lowers friction, and delivers noticeably better corrosion resistance than a typical phosphated bolt. Every bolt is fully MPI tested to confirm the material is sound before it ships, and the bolt lugs are chamfered at 45 degrees for reliable lockup even under high-pressure handloads and fast, lightweight actions.

Key Specifications

• Chambered in 5.56 NATO for AR-15 platforms.
• Bolt body machined from 9310 tool steel, exceeding typical mil-spec Carpenter 158 bolts.
• Finished with a black nitride treatment for increased surface hardness and reduced friction.
• Offers superior corrosion resistance compared to standard phosphated bolts.
• Every bolt is MPI tested to verify the material is sound and defect-free.
• Bolt lugs are chamfered 45 degrees for reliable lockup under high-pressure handloads.
• Extractor is machined from S7 tool steel and sprung with a spring, o-ring, and silicone insert.

Frequently Asked Questions

What makes a nitride bolt different from a phosphated bolt? Nitriding increases surface hardness, reduces friction during cycling, and offers noticeably better corrosion resistance than a standard phosphated finish.

Is this bolt tested before it ships? Yes — every bolt is fully MPI tested to confirm the material is sound and free of defects.

What is the extractor made from? The extractor is machined from S7 tool steel and sprung with a spring, o-ring, and silicone insert.

Buy the Faxon Firearms Black Nitride 9310 Bolt, 5.56 NATO AR-15

A bolt is one part you don’t want to cut corners on, and Faxon Firearms built this one to run harder loads with real material verification behind it. Browse our full AR15 bolts selection and order from our Lubbock, Texas gun shop for fast, direct shipping.