CMMG BOLT ASSEMBLY AR15

Description

The CMMG Bolt Assembly for the AR-15 platform is a direct replacement or spare bolt intended for shooters who want a ready-to-install unit without sourcing individual components. It ships with the ejector, extractor, and gas rings already installed, which means it can go straight into a bolt carrier group without additional assembly or fitting work. That matters when the goal is getting a rifle back into service quickly, or when building an upper and keeping the parts count manageable.

The bolt body is machined from 9310 steel, a nickel-chromium alloy commonly chosen for this application because its toughness under cyclic stress holds up well to the repeated camming and battering that a bolt endures over sustained use. The phosphate finish on the bolt provides a baseline level of corrosion resistance and holds lubricant in its surface texture, which is useful in wet or dusty conditions where a bare metal surface would dry out faster. The extractor is made from 4140 steel and carries the same phosphate treatment, giving it the hardness needed to grip and strip cases reliably without being brittle enough to crack under the forces involved in extraction.

CMMG lists this bolt as compatible with .300 BLK, .350 Legend, and 5.56mm — calibers that all use the standard AR-15 bolt face diameter, so a single assembly covers rifles chambered in any of those three. Every CMMG product is backed by their Lifetime Quality Guarantee, which covers the assembly against defects in materials and workmanship for the life of the part.