CMMG FourSix Review: First 4.6x30mm AR15 on the market

by Travis Pike

April 18, 2022



Are you ready for not only the first 4.6x30mm AR 15 on the market? Heck, are we even ready for the first 4.6x30mm weapon on the civilian market? Well, we better be because today we are reviewing CMMG’s latest, the FourSix. 

FourSix Specs

  • Caliber 4.6X30MM
  • Barrel Length 8 inches
  • Muzzle Device SV Brake
  • Trigger CMMG Single Stage
  • MSRP $1,399.95

The FourSix – A New Banshee 

CMMG never said they were going to produce an AR 15 in every caliber possible, but they dang sure seem intent on trying. CMMG produces ARs in a ton of calibers, from the standard 5.56 and 300 Blackout to 10mm, 9mm, 45 ACP, 5.7×28, and even a 7.62x39mm AR that takes AK magazines. 

The CMMG FourSix simply brings the 4.6x30mm round to the AR market and gives American shooters the first 4.6x30mm firearm for the civilian market. The FourSix comes as an AR pistol currently, but CMMG releases SBR variants of their rifles all the time. Why the FourSix, or should I say why the 4.6x30mm? 

Well, much like the 5.7x28mm, the round sits between a pistol and intermediate rifle round. It goes further than a pistol caliber and penetrates deeper but doesn’t have the same recoil, muzzle rise, and barrel length requirements as a rifle round. 

You get a very small and lightweight platform with more range, greater accuracy, deeper penetration without reliability issues, and the massive concussion and muzzle flash associated with short-barreled rifles. Specifically, barrels below 10 inches. The FourSix gives you a lightweight, easy handling platform with hardly any recoil or muzzle rise. 

The 4.6x30mm does have a big logistical advantage over the 5.7x28mm round. Specifically, it’s cheaper. Right now, it’s about 8 cents per round cheaper. Not much, but the 5.7x28mm has economy of scale on its side. The 5.7 requires a lacquer and makes reloading a pain. If the 4.6x30mm gets the same economy of scale, the price could be driven down exponentially.

CMMG FourSix Features

CMMG FourSix Features
1 Direct Impingement Gas System 
2 Multi-Cal compatible magazines
3 CMMG SV Brake 
4 M-LOK Handguard 
5 CMMG Ripbrace Included

The Fightin’ FourSix – Our Take

The CMMG FourSix falls into the Banshee series of firearms but doesn’t use the radial delayed blowback system. Instead, it uses a standard direct impingement system that uses a patent-pending micro gas block and micro length gas system. Going D.I. over blowback reduces recoil significantly. 

The 4.6x30mm isn’t a big powerful round by any means, and combined with the D.I. gas system, and the CMMG FourSix has hardly any recoil or muzzle rise. The SV brake must help a fair bit as well. Regardless, the FourSix handles a lot like a rimfire rifle. It barely moves between shots and is the most controllable centerfire AR I’ve ever run. 

I’d feel comfortable handing this gun to a new shooter. The light recoiling design won’t punish new shooters and won’t create an unsafe situation. At the same time, it’s a bit more fun than a simple rimfire rifle. 

Rapid-fire ensures you can get fast follow-up shots on target and do so very accurately. In a home defense situation, quick follow-up shots matter, and this gun dispenses them. On the accuracy front, the 4.6x30mm provides some impressive, flat-shooting performance out to 100 yards. At 150 yards, there is some slight drop, but it’s a quick and easy holdover. 

Shooting a gun this small, that recoils this little, at 150 yards provides me a sense of endless enjoyment. The trigger isn’t super impressive. It’s not a nice drop-in design, and it’s more of a refined mil-spec type trigger. Not remarkable, but not bad by any means. It’s plenty accurate, and 100 yards, I’m seeing two-inch groups when fired in a supported prone position. I feel comfortable and confident taking coyotes at 100 yards. 

Up close, you can shoot fast and accurately, thanks to the controllability of the weapon. Swinging from multiple targets feels natural and makes transitions a breeze. At 15 yards, I can pull off a rapid box drill that puts six rounds into two targets in less than 4 seconds from the low ready. Between 5 to 50 yards, you’ll absolutely dominate targets both big and small. 

These rounds are a lot closer to the 5.56 projectile in shape. This design tumbles when it strikes drywall and rapidly loses energy. This is great for home defense because the round is less likely to over-penetrate in the event of a miss. Ammo from Fiocchi seems to be common, and Liberty Defense makes some awesome self-defense loads. I’d love to see these loads hit the general market. 

The FourSix is so light and short you can also easily and reliably wield it with a single hand. If you have to escort kids, open doors, or something similar, then you can do so without dropping the FourSix. I even fired several drills wielding the weapon with a single hand. I easily drove rounds to the target with little difficulty. 

At home defense distances with a red dot, I’d have zero issues putting lead into a bad guy with a single hand. This gives the FourSix a decent advantage compared to the standard 5.56 caliber rifle. Also, the 4.6 round outperforms a standard PCC round. Best of all, it has less recoil than both. The FourSix could be called a PDW, but from the civilian perspective, HDW or home defense weapon might be a bit more applicable. 

The magazines are proprietary but are roughly the same size and shape as a standard 5.56 magazine. Sure, it’s a bit bigger than it needs to be, but it fits standard lowers, making it easy to buy a FourSix upper and use any lower you want. On top of that, you can use standard AR 15 magazine pouches to carry spare mags. The magazines hold 40 rounds and will cost $39.95.

CMMG asks $1,399.95 for the FourSix. Sadly there isn’t pricing on just the upper and bolt combo, but hopefully, that will pop up soon. Ammo is expensive, with brass-cased Fiocchi running about 80 cents a round. It’s not a new caliber, but it’s obscure on the civilian market, so the price is high. Popularity could drive the price now, but right now, it’s rather expensive. 

FourSix Pros and Cons

  • Lightweight and Short
  • Low Recoil and Muzzle Rise 
  • Accurate and Flat Shooting to 100 yards 
  • Magazines are compatible with standard lowers
  • Expensive Ammunition
  • Hard to Find Ammunition

Report Card


The FourSix shines in shootability. Recoil and muzzle rise are almost nil. They are barely perceptible, and the little 8-inch barrel makes great use of the 4.6 caliber round. It’s super easy to handle and sweet to shoot. 


In 400 rounds, I experienced no issues. The gun fires, extracts, ejects, and the new magazines feed without issues. 


It’s a solid AR with the AR ergonomics you know and love. They are solid, and you do get an oversized charging handle and an ambidextrous safety. Other than that, it’s a standard AR, so it’s easy and functional. 


At close and long ranges, the FourSix is pretty solid. It’s not a 1 MOA gun, but accuracy is perfectly acceptable. No one is putting this gun on the line at a PRS contest, but it’ll put lead where you want it. 


The price of 1,399.95 might be tough for some, but that’s a pretty standard price for a high-quality AR. The big downside will be the ammo and magazine cost. Ammo costs 80 cents a round on a cheap day, and 40 dollar magazines are far from cheap. 

CMMG FourSix Final Grade

Our Grade


Reviewed by Travis Pike

Reader’s Grade


Based on 4 Reviews

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The CMMG FourSix brings a new caliber not only to the AR world but to the civilian market. Not only does this give us a novel gun, but it provides us with a very lightweight, short, and sweet weapon that outperforms PCCs without the size and weight penalty of a 5.56 caliber rifle. 

CMMG FourSix Ammo

Range Rounds

Fiocchi Range Dynamics HK 4.6X30MM AMMO

Cost Per Round
Brownells $0.86

CMMG FourSix Starter Pack

If you’ve decided to pick up the FourSix, or found another firearm that suits your needs, there are some bare essentials you’re going to need to pick up in order to maximize its potential and your safety regardless of if it’s your first firearm or not.

  • Gun Cleaning Kit: Otis All Caliber Elite Range Box on Amazon or build your own personalized cleaning kit with premium components.
  • Shooting Glasses: All it takes is one piece of rogue hot brass, and you’ll learn the importance of shooting glasses. But not all glasses are built the same. See our recommendations for the Best Shooting Glasses.
  • Hearing Protection: Firing a gun without wearing proper ear pro can be very dangerous and detrimental to your hearing. Find out the best hearing protection for you in our full length review.
  • Storage: Check our our article on the Best Biometric Gun Safes
  • Targets – If you’re wanting a great resource for shooting practice or zeroing your optics on your optics rifle or pistol, download our FREE Sighting in Targets below.

Upgrades and Accessories

CMMG FourSix Accessories

Holosun AEMS
  • Compact Red Dot
  • Proprietary Mount
  • Multiple Reticles
Check Price
Blue Fore Gear Vickers ONE Sling
  • Light and Slim
  • Utilizes 1” webbing and custom designed hardware
Check Price
Streamlight TLR RM 2
  • White LED produces 1000-Lumens
  • 10, 000-Candela
  • 200m beam runs 1. 5 hours
Check Amazon
Decibullz Custom Molded Earplugs
  • Great In-Ear option
  • Custom molded – super easy and comfortable
  • NRR: 31
Check Amazon

Caring for Your CMMG FourSix

It’s critical not only to keep your guns secure, but also to understand how strip it down and care for it. In this video below we look at how to Field Strip the CMMG Banshee.


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About Travis Pike

Travis is a former United States Marine Corps Infantryman and currently a firearms writer, instructor, and works in Emergency Management.

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  1. I’ve had one in 4.6×30 for about a year now in midnight bronze…Loaded it up with gear,dual lasers,backup sights,light,thermal qd and a qd aim point pro,extended a mappul vg and single point m4 magpul sling…Still comes in at 7.11 pounds.
    The weapon is a joy to shoot…it’s perfect for CQC and I have had ZER0 FTF or Jams…

    Now if the ATF will start helping to protect this country and stop acting like they are congress passing this stupid pistol brace law…Maybe more people will buy one…

    I’m disabled veteran need to use a brace and now the ATF has made me a future fellon…I ve not even had a parking ticket in 40 years.

    US military retired

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