The bolt-action system first appeared in the early 19th century in breech-loading rifles such as the Dreyse needle gun. The firearm’s bolt has since come a long way in its evolution much like the many designs, inventions, and technological advances in firearms.
In today’s review article, we will be going through some of the best bolt carrier groups (BCG) you can get for your AR-10. But before we get into that, let’s first have a look at what a BCG is and how it works.
|Get The Best Deal
|CMMG – .308 AR Bolt Carrier Group
Most Recommended Option
1. Extremely durable
|JP Enterprises – .308 AR Low Mass Bolt Carrier Group
1. Preserve great strength
|DPMS – .308 AR Bolt Carrier Group
|1. Great option for someone look for something reliable
3. Easy to install
|Bravo Company – M16 5.56 Bolt Carrier Group
|1. High quality
2. Beginner friendly
3. Great for automatic rifle
|WMD Guns – M16 5.56 Nickel-Boron Bolt Carrier Group
|1. Hear-treated bolt
2. Solid as a tank
What is a Bolt Carrier Group (BCG)?
Modern firearms now demand more complex and sophisticated bolt units to support their firing systems. And the bolt carrier groups are the primary functioning part, a lifeline of your AR-15 and AR-10 rifles.
The Bolt Carrier Group is full of moving parts, it consists of 6 main components: the retaining pin, bolt cam pin, gas key, bolt assembly, carrier, and the firing pin. The bolt carrier group (BCG) can be found located between the upper and lower receiver in all AR-15 and AR-10s, as well as other AR-style guns.
The BCG endures extreme temperatures and pressures while it reliably performs three main functions: cycling, ejection, and reloading. The BCG will shoot off a cartridge, load a new one up, and expel the empty case.
Factors to Consider when Buying a Bolt Carrier Group (BCG)
Type of Bolt Carrier Group (BCG)
There are many different types of bolt carrier groups with different characteristics. If you are an AR-10 owner, then you’ll need to be familiar with phrases like Full-Auto Bolt Carrier Group, or the variety of material types, and acronyms such as HPT and MPI.
There is no mil-spec standard in the .308-bolt carrier group as you’ve likely seen with the AR-15 family, so the first thing that you need to do is that there are multiple incompatible .308-bolt carrier group designs. With this in mind, you can then only use an AR-10 BCG in Armalite AR-10 Rifles and DPMS LR-308 BCG for the DPMS .308 platform.
Generally, there are two common BCG profiles: semi-auto (SA) and full-auto (FA). The decision between them will depend on the intended use of the bolt carrier group. An FA or M16 style BCG is mostly favored due to its versatility and shrouded firing pin.
A carrier’s shrouded pin takes the force and applies it evenly to the hammer after every round, whereas an unshrouded firing pin triggers excessive wear on both the hammer and firing pin, which may cause your firing pin to break easily with hard use.
An FA carrier also has a little more material on the back compared to semi-auto bolt carrier groups (BCGs). This results in the SA carrier weighing less than full-auto (FA) carriers. Due to the cutback at the rear portion, you can use a lighter buffer for semi-auto carriers, resulting in more weight savings if you’re building your own AR-10 rifle.
The low mass of semi-auto bolt carrier groups also brings about other benefits, such as a minor recoil and a somewhat increased rate of fire. On the other hand, the FA BCG has more weight than the stock AR-15 BCG, and the greater mass works to offer more consistent reliability and function if your AR-10 rifle.
Another feature to consider in the BCG is its material. This is important as the bolt carrier groups face a lot of heat and stress and should be perfectly machined to deliver optimum performance. Bolt carrier groups made from old-fashioned steel is a classic choice for this piece of metal that slides back and forth with each shot.
Other common steels for manufacturing bolt carrier groups (BCGs) include the Carpenter 158 and 9310 steel for the bolt, and 8620 steel for the carrier. However, you may also find bolt carrier groups made from aluminum, titanium, and a hybrid mixture of all three elements on the market.
Other than the flawlessly machined bolt and parts, the finishing or coating of a BCG is an equally critical feature as it will affect how the bolt carrier group resists heat and corrosion. You will find a multitude of finishes, but the most common one would be the mil-spec, phosphate coated BCG as a standard. This is an economical, durable, and highly corrosion-resistant exterior. However, since it has a more porous surface, it can get quite susceptible to fouling and may be challenging to clean.
Hard coat chrome finish was an excellent alternative for years but has slowly lost popularity with the rise of newer coating technologies. Although the manganese phosphate coating is a standard on most regular bolt carrier groups, the newer coatings are more durable and require less lube to run smoothly.
According to Mil-Spec requirements, the bolt carrier interior and gas key must be chrome-lined to provide a smoother and corrosion-free surface on the inside. Assuming that every quality-made BCG has undergone heat treatment, the bolt carrier group should also go through a shot peening process which involves tiny shot spheres being blasted at the bolt to relieve stress from the metal.
Reviews of the Best AR-10 BCGs
Now let’s take a look at our recommendations for the best AR-10 BCG.
1. DPMS – .308 AR Bolt Carrier Group
Best AR-10 BCG – Best Overall
This bolt carrier group is the perfect option for ensuring your AR-10 functions well in any given situation. Whether you’re a hunter or a target shooter, you’ll surely want a fully functioning AR-10 rifle that will get the job done.
The AR bolt carrier groups remain to be the most common .308 BCGs available to dominate the .308 AR rifle platform. The DPMS pattern LR-308 is a shot-peened bolt that’s machined from Carpenter 158 steel alloy and 8620 carbon steel. The carrier is also chrome lined and available in either a mil-spec phosphate coating or hard chrome finish.
This is a complete AR-style .308 bolt carrier group that comes with the bolt carrier, gas key, gas rings, bolt assembly, ejector, extractor, cam pin, retaining pin, and the firing pin. The BCG would make an exceptional accessory for many AR-10 users thanks to its solid quality that allows for an excellent operation to make the Armalite rifle a whole lot more reliable in many situations.
So, if you want an AR-10 to work exactly the way you want it to, you’ll need to start with the “heart” of the AR-10 rifle – the bolt carrier group.
Recent buyers were very happy with this bolt carrier group. It’s easy to install while being super durable and lightweight to not add any additional weight to the rifle itself. Some have also noted that the headspace on the BCG was perfect and allowed for a really good fit. Despite the superb, reliable functioning, several customers have complained about the finishing that has noticeable traces of the machining process and a very tight fit between the BCGs and uppers, which may prevent cycling.
The bottom line is that the DPMS .308 AR Bolt Carrier Group is a solid option that will get your AR-10 in working order. All you need is to install this onto your AR-10 rifle to watch it run like a well-oiled machine. This is a genuine factory replacement that’s the closest unit to a “standard”. The main difference you’ll spot is the absence of Forward Assist serrations.
You would like this if:
You want something easy to install. The BCG comes fully assembled and drop-in ready direct replacement for you to set it up in your rifle within minutes.
You might not like this if:
You want good finishing. There have been several complaints that the finishing is not perfect and the new bolt appears to be a bit tight inside the carrier.
You want a versatile BCG. This bolt carrier group also works with a 6.5 Creedmoor caliber.
2. JP Enterprises – .308 AR Low Mass Bolt Carrier Group
Runner-Up for Best AR-10 Bolt Carrier Group
This AR-10 BCG is machined from an extremely durable stainless steel that’s been proven to be physically tough and easy to install for a better functioning AR-10 rifle. Aside from making your AR-10 more enjoyable, the BCG also keeps the AR-10 rifle cool in extended periods of precision shooting, making this an important building block for those who frequently spend a few hours at the range and hate the idea of an overheated AR-10 rifle.
JP Enterprises is one of the first AR-parts manufacturers that started producing lightweight BCG models. The Low Mass Bolt Carrier Group is made from SAE 9310 stainless steel and treated with chromium nitride finish and reduced weight cuts without sacrificing strength. This JP lightweight carrier also comes with extra bearing surfaces to enhance bolt alignment, reduce wear and tear as well as to allow for a lighter recoil impulse.
One thing that you need to take note is that the lightweight bolt carriers have significantly lower reciprocating mass compared to the standard mil-spec carriers and hence need an adjustable gas block for less gas flow and softer recoil. Another thing you’ll notice on the JP Low Mass Carrier is the missing forward assist extension, but since the model is only used in rifles meant for competition, this feature will not be missed.
These bolt carrier groups would make an excellent product for those who want to extend their rifle’s longevity. The heat from frequent firing can shorten the AR-10 rifle’s lifespan and reduce overall performance if it consistently gets hot with each and every use. So, this bolt carrier group would be a good place to start to keep overheating issues to a minimum.
Many new customers have expressed satisfaction with the overall functionality of the bolt carrier group. One of the many benefits that made this a hit among shooters is the ability to reduce a good amount of felt recoil. Many have noticed a significant reduction in felt recoil upon installation to result in more accurate shots.
Overall, the JP Enterprises .308 Low Mass BCGis designed to ensure your rifle stays cool and to remain as functional as possible for a long time. If you’re looking for superior durability and heat dissipation that’s hard to rival, then this BCG might fit the bill.
You would like this if:
You don’t want excess weight on your rifle. The bolt carrier group weighs only at 8.9 ounces and is very lightweight.
You want a durable BCG. The BCG has a chromium nitride finish coated bolt and Melonite QPQ (Quench Polish Quench) coat carrier for enhanced longevity.
You have a tunable gas system. The BCG has oversized carrier bearing surfaces and works perfectly for AR-10 rifles with tunable gas systems.
You might not like this if:
You’re a budget shopper. Although this is definitely a great bolt carrier group AR10, it does not come cheap and may be a little too expensive for certain budgets.
3. Bravo Company – M16 5.56 Bolt Carrier Group
5.56 AR-10 BCG Runner-Up
Battle-tested for all the hardcore uses, this BCG is perhaps one of the toughest available on the planet. The bolt carrier group is heat-treated, peen-tested, and has passed many quality and reliability tests with flying colors before even hitting the shelves for sale. So, if you place quality and reliability as of great importance, then this is the type of accessory that will give your AR-10 more functionality than subpar factory defaults.
It is without a doubt that the BCM M15 5.56 BCG is one of the best selling and most popular AR-15 bolt carrier groups available that does not come with any unnecessary exotic coatings (such as black nitride or titanium nitride) or other less proven gimmicks. It does what it’s meant to do – to satisfy different necessities and precision shooting styles.
Bravo Company Manufacturing offers a fully assembled bolt carrier group with a parkerized exterior. The carrier and gas key has a chrome-lined interior while the bolt assembly is constructed from a mil-spec carpenter no. 158 steel while the extractor spring is made from tool steel.
As a standard, all BCM BCGs are staked with grade 8 hardened fasteners, magnetic particle inspected (MPI), and heat-treated (HPT) for better durability. After machining, the bolt is then shot-peened for increased strength and higher heat resistance. On top of that, each unit of BCG is even thoroughly test-fired for function before being shipped out.
This is yet another bolt carrier group that is suitable for general shooting purposes. If you just want an upgrade from your factory default BCG, then this would offer you a good opportunity to do so. Once you’ve got this installed, you’ll notice an immediate change to your existing rifle setup.
Many shooters commended this bolt carrier group’s ability to stay cool while they fire off their rifles for extended periods of shooting (i.e. target shooting). They were able to test it out at the range for a few hours of continuous shooting thanks to the significant amount of heat dissipation.
The Bravo Company is known for making high-quality and solid accessories, and this bolt carrier group is no exception. Although the Bravo unit is primarily built for first service semi-automatic rifles, this bolt carrier group features a full-auto profile, making it compatible with fully automatic AR-10 pattern rifles too. Just by knowing that the US Navy, US Marines, and SOCOM are on the Bravo list of clients means that you can be assured that this product would make a great addition to your AR-10.
You would like this if:
You want something easy to install. The BCG comes fully assembled for you to set it up in your rifle within minutes.
You want a durable BCG construction. The bolt carrier group is made with mil-spec carpenter no. 158 steel with grade 8 hardened fasteners and a tool steel extractor. It is made of military-grade materials and conforms to all military specifications.
You have an automatic-rifle. This bolt carrier group is designed to fit full-auto versions of your AR15 or M16.
You might not like this if:
You’re a budget shopper. Although this is definitely a great bolt carrier group, it does not come cheap and may be a little too expensive for certain budgets.
4. CMMG – .308 AR Bolt Carrier Group
Best AR-10 BCG for the Money
This bolt carrier group is hands-down one of the most solid BCGs on the market that’s made for hardcore stuff. So, this would be a great choice for those using their AR-10 for tactical situations or for long periods of target shooting. This high-quality accessory is worth every penny especially considering that it has a very straightforward installation.
The complete CMMG bolt carrier assembly comes with a bolt, bolt carrier, staked gas key, cam pin, stainless steel firing pin, and a retaining pin. The AR10 BCG bolt is built from 9310 steel while the carrier is machined from 8620 steel with a chrome-lined interior. Finally, the extractor is fabricated from hardened S7 tool steel.
All components in the BCG feature a durable phosphate matte black finish while both the bolt and carrier are magnetic particle inspected and shot-peened. Just like the other variants mentioned in our guide today, the CMMG BCG comes without the forward assist serrations.
Overall, this is a great BCG for those who use their AR-10 rifles for high-stress situations. Whether you’re in law enforcement or the military, or simply a shooter that enjoys spending all day shooting at targets at the range, this lightweight and durable BCG will be at the top of your list of potential choices.
The CMMG AR Bolt Carrier is designed to be hardcore and to handle all your AR-10 functionality needs right after installation. You’ll be hard-pressed to find another one that is just as durable and reliable at this price point. Although this does not have the smooth fitting feel or other bolt assemblies, it is made under a standard that is most widely used for bolt carrier groups.
You would like this if:
You want a durable BCG construction. The bolt carrier group is made from 9310 steel with phosphate finish and 8620 steel chrome lined, phosphate finish carrier. It’s also magnetic particle inspected and shot-peened.
You might not like this if:
You want to use it right out of the box. Made for heavy-duty usage, this also means that it may take a while to break in due to the very rough operating requests.
5. WMD Guns – M16 5.56 Nickel-Boron Bolt Carrier Group
Best 5.56 NATO AR-10 BCG for the Money
This good looking BCG is made from a mix of nickel and boron. Aside from its beauty, this accessory was made to kick butts and take names as proven by its heavy-duty usage of an AR-10. WMD Guns is a leader in the coating technologies and their BCG feature proprietary NiB-X nickel boron finishes that will allow for extremely extended periods between cleaning cycles. This BCG also comes with full forward assist teeth, a properly staked gas key, and a classic M-16 cut profile.
This WMB BCG assembly utilizes the massive M16 Full Auto carrier, which will also function in any semi-automatic AR-15. The carrier body is made from case hardened 8620 with next-generation NiB-X Nickel Boron Coating that offers 40% greater wear life than mil-spec coating.
The AR-10 bolt is also heat-treated from 158 carpenter steel and is shot peened plus magnetic particle inspected (MPI). On top of that, the BCG is also available in semi and fully automatic models, with or without a hammer certified as per Government drawings.
We expect this BCG to be highly popular among tactical and even competitive shooting users. Such heavy usage will require something tough enough to handle long periods of shooting and this indestructible BCG is the one for the job.
Many users had only great things to say about the BCG’s durability. It is lightweight, tough as a tank, and is best for tactical and hunting applications. Many were also able to install it easily without the need for advanced gunsmithing skills.
The bottom line is that the WMD M16 nickel-boron bolt carrier group certainly stands out from the rest as the go-to BCG for most frequent AR-10 users. This BCG will last you long enough to go through years or even decades. All-in-all, the bolt carrier group comes with cutting-edge coating for high-volume shooters or anyone planning to use their AR-10 rifle in a dirty and sandy environment. With minimal or no lubrication required, this durable and low maintenance bolt carrier group will definitely make your investment last longer and function smoothly.
You would like this if:
You want a durable BCG. The bolt carrier group has a slick finish and NiB-X to reduce friction and keep carbon from adhering. It also features WMB’s proprietary NiBX nitride finishes that offer 40% more wear resistance than chrome.
You want an easy-to-install BCG. The BCG comes fully assembled and drop-in ready direct replacement for you to set it up in your AR rifle within minutes.
You might not like this if:
Other than the barrel, the bolt carrier group is often referred to as the heart of an AR-rifle. However, the diversified choices of BCGs on the market can make purchasing the best BCG for your rifle a confusing task. While there are some that have been designed to be professional and general at the same time, several such upgrades are specialized units like lightweight bolt carrier groups that are made to ensure top-performing results at competitions and ranges.
One should also know that most issues and problems with the AR rifles have to do with the BCG, so if you happen to make the wrong selection, you may just have to suffer through a less enjoyable firing experience.
Hopefully, today’s article has given you enough info and comparison to pick the best AR-10 Bolt Carrier Group for your rifle. Remember to check out the specs and feedback from someone who’s had a go with your chosen BCG.
Hello there, it’s Michael here. A gun lover since young, served the country for the last 20 years. I started the blog to share my experience and gun-related knowledge accumulated throughout the years. Hopefully, you will find something useful over here or just have fun! You can learn more about me here.