If you are currently looking for the best 9mm BCG for your AR-9 carbine, youâve come to the right place.
Any complete AR-9 upper will come with a BCG. But if you’re building your own rifle or you’re interested in upgrading your current one then knowing a little about why and what the BCG does will help a lot in picking the right one for you.
For durability and reliability, the BCG is the most critical part of the rifle. So don’t cheap out and get the lowest-priced thing you can find. That said, AR-9s aren’t like AR-15s and their BCG is far less complex. The difference in reliability that you’ll see between a mid-tier BCG and an upper-tier BCG isn’t as much as you’d think it is.
By the way, did you know there are AR-15 9mm conversion kits that let you convert your 5.56 lower to accept 9mm magazines? Definitely worth looking into if that’s an option for you.
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Why Go With The 9mm Round For An AR?
Why would you want to go with a 9mm Luger for an AR, to begin with? After all, the vast majority of AR rifles and carbines are chambered for rifle rounds such as the 5.56x45mm NATO, which offer much greater range and superior ballistics than pistol rounds such as the 9mm.
While it is true that the 9mm rounds lacks a lot of the power, range, and energy of a rifle round such as the 5.56, there are still a handful of reasons to consider getting a 9mm AR.
The first reason to get an AR9 is for ammo commonality. Many service pistols such as the Glock 19, Beretta 92FS, Smith & Wesson M&P, Walther PPQ, and so on are chambered for the 9mm Luger round, which is the most common pistol round in the entire world.
By having one round for both your carbine and your pistol you can interchange the ammunition between both weapons.
In some cases, you can even interchange the magazines. For example, most AR-9 pistols will accept Glock 19 length or longer 9mm magazines.
If you have a Glock 34, Glock 17, or a Glock 19 for your handgun, you can use the same magazines for both weapons. This can make for a neat and convenient setup for home defense, bugout bags, competition, and just plinking at the range.
9mm ARs also (generally) have less felt recoil making them easier and more comfortable to shoot. This is especially helpful if you’re a smaller shooter.
On the home defense side, AR-9s can have much shorter barrels without losing much of their ballistic performance and are easier to suppress. Get some 147gr 9mm and a suppressor and you’ll have a near-silent home defense weapon.
Speaking of shorter barrels, small weapons are always easier to maneuver in tight spaces. An AR-9 pistol is a very compact shooter!
Lastly… they’re just really fun. If you’re a recoil junkie, maybe they won’t be as interesting to you — but for the rest of us, they’re just a lot of fun to shoot. Small, light, compact, easy to blast with, and using ammo that won’t break the bank. That’s a very attractive little package right there!
What Is The Bolt Carrier Group?
Put into simple terms the bolt carrier group is the beating heart of an AR-15 rifle.
The bolt carrier group is also a part of the upper receiver to an AR-15. When you install it, youâll slide it into place through the rear of the receiver until it locks into place.
How the bolt carrier group works In a normal AR-15 (note, not an AR-9) is when you fire a round, the gas will be redirected from the spent cartridge from the barrel and into a gas tube to travel back into the bolt carrier’s gas key.
The gas flows through the key and will fill up the chamber inside the BCG behind the bolt that has been created by the gas rings of the bolt, this forces the bolt to act like a piston and pushes the mass of the carrier backward. The carrier going backward forces the bolt to turn, unlock, and the BCG cycles.
But… that is in a normal AR-15 BCG. 9mm BCGs are much more simple.
A normal AR-15 BCG is made from several different parts, but 9mm BCGs are normally made from basically one piece of steel.
While a normal AR-15 is built with a locked breech and uses a form of direct impingement to function, an AR-9 is normally simple blow-back. The gas pressure of the chamber itself is what forces the bolt backward to cycle.
What keeps the system safe and functioning is the weight of the BCG and the spring holding it closed.
The Gas Key on a 9mm BCG is there to give the charging handle something to hold onto, it doesn’t actually handle any gas. And there is no moving bolt since nothing locks into the barrel extension.
Other than an extractor, ejector, and the fake gas key — an AR-9 BCG is basically just a lump of metal.
Buyerâs Guide For A 9mm Bolt Carrier Group
For a normal BCG in a normal AR-15, we strongly recommend that you never buy one that you can’t confirm as being MPI and HPT tested (more on that in a moment).
But for 9mm BCGs, most of them simply aren’t MPI or HPT tested because the pressures involved are so much lower than a rifle cartridge.
Some brands still run MPI and having a BCG that passed MPI is a lot better than one that didn’t. But as far as I’ve seen, almost no one HPT their 9mm BCGs. This isn’t a bad thing, just something to know.
MPI means magnetic particle inspected.
Bolt carrier groups, as weâve discussed, are literally the beating heart of your 9mm AR carbine.
If any part of your BCG at all suffers a crack or a fissure, then the entire firearm could have a catastrophic failure (meaning it could literally blow up in your arms). To prevent this, many BCGs are tested via magnetic particle inspection.
The BCG is placed into a magnetic field created by two electromagnets and submerged in a liquid solution of magnetic particles. Add in some fancy cameras and the cracks and fissures located on or beneath the surface are quickly shown.
Avoid any 9mm BCG that does not come certified with an MPI.
That said… for some reason, many BCGs don’t actually tell you that they are MPI tested and if they are if it is individual testing or batch testing. If you really want to know, try Googling the name of the BCG + “MPI tested” and see what happens. Lots of times you’ll find people that can say for sure or if the manufacturer has said so themselves.
High-Pressure Testing is basically what it sounds like. The manufacturer loads up a cartridge extra hot and fires it in the BCG.
These extra-powerful cartridges are designed to be WAY more powerful than what the BCG should normally ever shoot. In fact, feeding your BCG a steady diet of these proofing cartridges would be very bad.
But doing it once in a controlled setting proves that the parts involved are strong enough to handle even the worst-case scenarios.
Very few 9mm BCG makers use HPT testing though.
Coat Vs. Glock
This might be the biggest thing to look for first — so pay attention!
There are two major ways of making an AR-9, one uses Colt SMG magazines and the other uses Glock 19/17/34 magazines. Both are great, easy to find, and about the same price.
Colt magazines are easier to load, look cooler, and are metal.
Glock magazines are more common, have cross-compatibility with Glock pistols, plastic, and are cheaper.
There is no right or wrong answer here, just pick the system you like best and run with it. But make sure your BCG works with your platform!
These days, you won’t normally see many BCGs that aren’t able to function with both magazines, but they are out there. Double-check the fine print.
Honestly, the largest difference in 9mm BCGs are their coating. Fundamentally, a 9mm BCG is a chunk of metal that doesn’t really do much other than add mass to the system. Because of that… there isn’t much to do to make them better than the others.
Coatings are the biggest area where one BCG can outshine the others. What coating is best depends on your application, but here are some pros and cons.
Nitride Coating: The most common “upgraded” coating for BCGs. Nitride is a chemical treatment that hardened the surface and makes it far more resistant to corrosion. While not as fancy as some other coatings, it works really well and provides a solid boost over a “mil-spec” coating (there is no mil-spec for AR-9s, I mean normal M4 BCGs).
Hard Chrome: Basically, you coat the BCG in chrome. This was the coating of choice by Eugene Stoner, hard chrome is a very good coating — but it’s hard to apply. As such, it lost a lot of popularity because there aren’t many companies that can do it right. Done right, hard chrome is easy to clean, smooth, super corrosion-proof, and just wonderful to use. Done wrong and it will flake off and cause a lot of problems.
Nickel Boron: Literally what the name suggests, this is a coating made of Nickel and Boron (95/5%) that is then applied to the BCG using electroless. The results are pretty great, slick, smooth, very resistant to corrosion and can even be run with less lube. But… Nickel Boron is known to wear down/off over enough use. Granted, that’s tens of thousands of rounds so rarely is it a problem for people — but it will happen.
NP3: This is basically Nickel Boron with some magic fairy dust. The magic fairy dust is namely polytetrafluoroethylene — you might know it by the brand name Teflon. This includes all of the awesome properties of Nickel Boron but with the added dry lube of Teflon. That’s pretty amazing, right? Well, yes but also no. This is a great coating, no question there. But producing polytetrafluoroethylene is pretty bad for the environment so this coating really isn’t “green” and is significantly more harmful to the environment than these other coatings. It also wears out like Nickel Boron does, because it basically is Nickel Boron just more slippy.
Parkerized: This is the “mil-spec” coating (for M4s at least). It’s durable, cheap, easy, and good. But it’s also really rough, ugly, and harder to clean. But again, durable and cheap.
Vapor Deposition Coatings (TiN, PVD, CVD): This covers a lot of coatings technically and they are not all made the same. PVD and CVD are processes for applying an alloy on the BCG, there is a lot of technical details, but bottom line is that an alloy is turned into a vapor and applied to the BCG. The most common is Titanium Nitride (TiN). But there are lots of others, most of them proprietary. I love PVD/CVD coatings, TiN is super slick, super pretty, and awesome all around. But they normally aren’t cheap.
Last but not least, cost matters. When youâre assembling your AR9 especially, all of the parts are going to add up in cost, and they can add up quickly.
As a golden rule, bolt carrier groups typically cost anywhere from one hundred to three hundred dollars depending on the group. You shouldnât need to pay anymore beyond this general price range.
The Best 9mm Bolt Carrier Groups For 2022
Now that weâve covered why you need to upgrade your 9mm bolt carrier group and what to look for in one, here are our top three choices for the best 9mm bolt carrier groups for 2022:
Faxon Firearms 9mm Bolt Carrier Group
The Faxon Firearms 9mm Bolt Carrier Group is simple, awesome, and very useful. It’s my go-to pick for a simple plinker and mine has been working great for years.
- Very easy to install
- Solid overall performer
- Simple but durable Nitride coating
The JP Enterprises AR-15 9mm is… expensive. I know. But this is a BCG that is built to be beaten and run hard for things like competition.
Overall, if you want a 9mm bolt carrier group of the utmost durability and reliability and are willing to pay a premium price for it, then the JP Enterprises bolt carrier group deserves your close attention.
- Excellent choice for prolonged shooting sessions
- QPQ Coating
- Incredibly durable
- Very easy to install
- Very expensive
- Glock magazine only
CMMG Radial Blowback 9mm BCG & Barrel
This is a radical (get it?) departer from what we’ve looked at before.
While 99% of the 9mm pistol caliber carbines on the market use simple blowback to make their actions work, CMMG went a huge step further and developed a whole new way of doing things.
Designing something they call “radial blowback” is basically a turning bolt that very closely mimics the action of a normal AR-15 BCG in that it turns and locks into the barrel. But this is absolutely not compatible with a normal AR-15, instead, this BCG has a cam path cut much more aggressively so that the pressure of the chamber is all that is required to force it open.
However, because that pressure has to overcome the mechanical locking of the turned bolt and cam path, this slows the operation down slightly and gives the rifle a much softer felt recoil and much less barrel flip.
If you’re doing something like PCC competitions, this might be very appealing to you.
The downside is that this is a proprietary system. That means you’re locked into a CMMG barrel and BCG and this isn’t cheap. But it’s not as bad as you might think.
$420ish for a barrel and BCG makes it $210 for each and that’s not a bad price for two great prices of kit.
- Cool engineering
- Durable design
- Absolut minmum felt recoil
- Competition ready
- Very expensive
- Cannot mix and match BCG/barrel
Either of these carrier groups for a 9mm AR that we have covered here today will be a solid option, and furthermore, you can also choose any other bolt carrier groups floating around on the market that follow the buyerâs guide section we listed out above as well.
Remember that the bolt carrier group is the beating heart of your 9mm AR carbine. It directly impacts the shooting performance of your carbine, and without it, you couldnât even shoot your carbine to begin with!