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Precision-machined (and upgraded) in the U.S.A. Our M16-profiled bolt carrier group is manufactured using properly heat-treated 8620 and 9310 tool steel, affording identical performance and reliability to units with C158 bolts at a much lower price. Each bolt and carrier receives quality gas seals on every bolt. Extractors are upgraded to S7 tool steel, affording…
So you just built a larger-sized AR chambered in either .308 Winchester, 6.5 Creedmoor, or even .243 Winchester, but you know what? Unless you want it to be nothing more than a replica or a life-sized prop, you’re gonna need to install the guts too, to get it to function. The “guts” of the upper…
You’ve meticulously picked out the parts needed for your new AR9 upper, and now you need that final piece that is going to breathe some life into. Made in the USA, this AR9 Bolt Carrier Group is machined from 8620 Steel that ensures a high durability and longevity and features an enhanced firing pin as…
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.
Our Bolt Carrier Specs:
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.
“Is an M16 bolt legal?”
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.
DISCLAIMER: If you are new to the world of DIY gun building, you likely have a lot of questions and rightfully so. It’s an area that has a lot of questions that, without the correct answers, could have some serious implications. At 80-Lower.com, we are by no means providing this content on our website to serve as legal advice or legal counsel. We encourage each and every builder to perform their own research around their respective State laws as well as educating themselves on the Federal laws. When performing your own research, please be sure that you are getting your information from a reliable source.
