Mil-spec M16 BCG assemblies available for completing (or upgrading) your AR-15.
You can't -- really, shouldn't -- reinvent the wheel. But you can always put better tread on it. That's why we're offering up M16 bolt carrier groups with improved, heat-treated 9310 bolts, mil-spec 8620 carriers, and new nitride treatments that provide better wear and rust resistance and natural lubrication compared to phosphate and chrome lining. Every gas key on every BCG we sell is heat-treated and nitride-treated, too, before being fastened with Grade-8 fasteners that are each properly staked.
Want to know more? Check out the AR Bolt Carrier Group Guide.
Building a 9mm AR pistol? Or a bench-ready .308 or 6.5 Creedmoor rifle? Grab a quality bolt carrier group to complete your build. Our 9mm BCGs are compatible with all available 9mm uppers, lowers, build kits, and other 9mm AR parts we sell. Available 9mm bolts are also ramped and work with PSA 9mm upper assemblies. All .308 parts, uppers, lowers, and components are also compatible with our available .308 nitrided BCG.
Just because something is "mil-spec" does not mean it's optimal, or even nearly the best choice, when it comes to overall performance and quality. Mil-spec simply means that a particular tool, alloy, or component adheres to basic standards. That's the case with the old Carpenter 158 steel originally used to craft mil-spec bolts.
Enter 9310. This is an AISI standard grade of tool steel that, when properly heat-treated, is approximately 7% stronger than Carpenter 158. With heat treatment, 9310 provides a slightly higher toughness that improves fatigue life of the bolt - an important quality, considering the bolt experiences the most heat and pressure from the AR's direct-impingement gas system. Importantly, 9310 also provides better corrosion resistance than C158, which allows it to withstand all that carbon fouling present in the gas system. In combination with nitride quenching, these 9310 bolts outperform the old "mil-spec" standard.
Need help with install or maintenance? How's how to disassemble your BCG.
Yes. Owning an M16 bolt, and using one in your AR-15, regardless of its configuration, is entirely legal. Using an M16 BCG will not make your AR rifle or pistol fully automatic. Why use one? Because it's a tougher, better bolt. Simple. That's why we include an M16 BCG in all of our build kits. The added mass of the M16 bolt carrier body also helps to reduce felt recoil, providing more inertia against the force of the bolt being pushed by the gas system.
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