Whether you’re interested in building your own AR-15 or AR-10 or just want to upgrade an existing rifle, you’ve probably debated what to do about the BCG (bolt carrier group). The BCG is considered by many to be the heart of the AR platform, and rightly so. The right — or wrong — BCG can make or break the gun and that’s why it’s smart to choose your BCG carefully. We have some suggestions for well-made, reliable BCGs for different applications. Check out our top five BCGs for AR platforms and get to creating the rifle you really want.
FailZero AR-15 EXO Coated Bolt Carrier Group
The FailZero line of BCGs is well known for superior performance and fantastic use of nickel boron. The AR-15 EXO Coated BCG is a well-made, reliable BCG that’s designed to keep your rifle cycling dependably. It ships fully assembled so there’s no need for you to put parts together yourself. It utilizes the company’s popular nickel boron technology, which provides dry lubricity, according to the company. While we do not recommend running your AR dry — that goes for any and all ARs — the FailZero EXO does run better and more smoothly as lube runs dry than many others. This BCG offers reduced friction, above-average performance, and stellar durability.
Features of this BCG include an M16 cut carrier and nickel boron coating on numerous parts including the bolt, extractor, and firing pin. This BCG is magnetic particle inspected (MPI) and high pressure tested (HPT). It weighs 11.4 ounces and is easy to clean at the rare times it becomes truly necessary. The bolt on this BCG is made from Carpenter 158 Steel which is a chrome nickel alloy steel known for fantastic resistance to wear and excellent strength. This is a tried and true BCG that’s proven itself as a durable, reliable performer.
Aero Precision AR-15 Pro Bolt Carrier Group, Black Nitride
Aero Precision has been designing and manufacturing fantastic AR parts for years. Not only do they offer reasonably priced components but the products they provide are made with an eye for detail and dedication to quality. The Aero AR-15 Pro BCG in Black Nitride is an excellent choice for builders. It’s built from the ground up to not only meet but exceed the demands of dedicated shooters in even the most extreme conditions. Every part is deliberately chosen to increase the reliability and provide an impressive service life of the bolt carrier group and its components. It’s machined from 9130 steel which is an alloy steel often used on aircraft and offers great shock resistance.
The AR-15 Pro BCG from Aero has a counter bored cam pin channel and is shot peened, MPI tested, and heat treated using the company’s proprietary flash nitriding process. Attention to detail is truly impressive. For example, cam pins are precision ground, extractors have a phosphate finish, and the carrier itself is made according to exacting tolerances. The gas key is torqued to spec and staked. Basically, it’s an extremely well-made BCG that should be your go-to as a builder.
Brownells Titanium BCG DLC
The use of lighter weight yet shockingly durable material has become increasingly popular in the AR world and that’s pretty evident with the titanium BCGs. The Brownells Titanium BCG DLC (Diamond Like Carbon) might look a lot like their standard nitride finish model, but it’s different. This BCG is made using 6A1-4V titanium which is a high-strength alloy with incredible corrosion resistance and fantastic strength. The bolt itself is made from 9310 tool steel.
A diamond-like carbon coating provides this BCG with an additional layer of quality. This coating reduces friction, improves resistance to wear, and delivers a higher-performing BCG across the board. The Brownells Titanium BCG DLC weighs in at a mere 7.9 ounces and is compatible with 5.56 NATO, 223 Remington, 300 Blackout, and 204 Ruger. This BCG ships assembled with torqued and staked gas keys. And while it does require a greater investment financially, it’s one of the best-priced titanium BCGs currently on the market.
Faxon 5.56 M16 Bolt Carrier Group, Nitride
Another company that’s built a reputation for producing high-quality parts is Faxon. Their 5.56 M16 Bolt Carrier Group, Nitride, is a great example of their dedication to designing reliable, long-lasting parts. Faxon created this BCG for optimal performance and hard use. It’s made using quality materials to ensure durability and longevity because AR owners need a BCG that lasts. The nitride finish on the carrier and bolt delivers superior corrosion resistance which makes it a solid choice for use even in the harshest elements. This BCG is full-auto-rated, meaning it can stand up to serious, dedicated use.
The entire design of this BCG is enhanced for smooth and consistent cycling. Faxon created the 5.56 M16 Bolt Carrier Group, Nitride, for both novice and experienced gun enthusiasts. 9310 tool steel is used for the bolt itself and nitride is used for superior surface hardness. Bolts are MPI tested and bolt lugs are chamfered 45° for reliable performance no matter what. As for the gas keys, they have grade 8 fasteners and are staked. Faxon did a fantastic job on this BCG and the proof is in the reliable cycling.
Sons of Liberty Gunworks 308 MK10 BCG
We’d be doing everyone a disservice if we didn’t include an AR-10 BCG. After all, although the AR-10 isn’t as commonly built or, frankly, upgraded as the AR-15, it’s a fantastic platform. The Sons of Liberty Gunworks 308 MK10 BCG is a beautifully constructed assembly that’s designed to deliver truly superior performance. This is a precision machined BCG created for the demanding AR-10 building or owner. It’s made from chrome-plated steel with a nickel-plated steel bolt for excellent corrosion resistance and the ability to withstand serious use.
The bolt finish on this one is Nickel NP3 which is designed to be a self-lubricating composite that’s long-lasting. This finish gives the bolt a slick, hard finish that makes it more durable and enhances cycling. It’s the same high-quality BCG Sons of Liberty Gunworks uses in their popular MK10 line of rifles, so if you admire their complete rifles but have a gun you’d just like to upgrade, this is the bolt carrier group for you. Yes, it’s a significant investment, but it’s well worth it. You don’t want to cut corners in any AR, and the AR-10 especially requires extremely durable, quality parts.
When choosing a bolt carrier group, remember to check the bolt face size and also the general construction. A skeletonized or otherwise lightweight BCG might not be ideal for a particular build or factory gun. Do your homework to ensure the BCG you select can and will perform as needed.
What’s your favorite bolt carrier group? Share your thoughts in the comments.
