Expo Arms 7.62x39 Nitride - Bolt Assembly

The Expo Arms 7.62x39 Bolt Assembly is a complete replacement bolt assembly machined from 9310 tool steel and finished in black nitride, designed for mil-spec AR-15 bolt carriers running 7.62x39mm upper receivers.

Building a reliable 7.62x39 AR-15 starts with a bolt assembly that can handle the cartridge's extraction demands — the Expo Arms 7.62x39 Bolt Assembly is purpose-built for exactly that:

S7 tool steel extractor for positive extraction: S7 tool steel is chosen for its ability to absorb the sudden, high-impact loads generated when pulling 7.62x39mm cases from the chamber.

9310 tool steel bolt body for long service life: 9310 is a high-strength alloy steel that balances toughness and fatigue resistance for sustained high-pressure cycling — delivering reliable function for thousands of rounds in a 7.62x39mm AR-15 build.

Black nitride finish for added surface hardness: Nitride treatment penetrates the steel surface to increase hardness beyond what the base material provides alone, improving wear resistance and delivering superior corrosion resistance over phosphate alternatives.

• Type: Bolt Assembly
• Caliber: 7.62x39mm
• Bolt Material: 9310 tool steel
• Extractor Material: S7 tool steel
• Finish: Black nitride
• Compatible Platform: Mil-spec AR-15 bolt carriers

Expo Arms delivers mil-spec and performance AR-15 components at competitive prices without compromising quality. Backed by Expo's Limited Lifetime Warranty against defects in materials and workmanship.