CMMG’s 9mm Guard: Revolutionary Pistol-Caliber AR Evolved

The Guard is CMMG’s revolutionary AR-based pistol-caliber carbine, or PCC, chambered for 9mm Luger. This is not another Colt clone. The Guard uses what CMMG calls their Radial Delayed Blowback system. Available in six models including pistols and carbines, the Guard has fully functional AR controls and feeds from Glock-pattern magazines.

CMMG’s delayed blowback system uses a two-piece bolt and bolt carrier. And though it appears to have a standard AR15 bolt carrier group, the Guard bolt is different in some important ways. Like blowback bolts, the bolt key is only there to grab the charging handle.

As the recoil impulse travels into the bolt and bolt carrier, the bolt has to rotate before it can clear the locking lugs. As it rotates it cams against the weight of the bolt carrier, buffer and spring, which keeps the action closed until the pressure drops and cycles like a standard AR.

With this system Guard bolt and buffer weights are much lighter which means less felt recoil. The combined difference in weight of the bolt carrier group and buffer, comparing straight blowback to Radial Delayed Blowback, can be as much as 6.5 ounces. CMMG offers an Action Tuning Kit that you can use to adjust the bolt weight, which allows users to tune the gun for use with different ammo and suppressors.

Another feature of the Guard is that it has a real bolt hold open, something many pistol-caliber ARs lack. This slows down reloading and conflicts with the standard AR manual of arms. The Guard has a fully functional last round bolt hold open with a dual-pinned, fully machined bolt catch linkage that uses a standard bolt catch spring. It works every time with factory Glock magazines.

This Guard is has a Burnt Bronze Cerakote finish.  I used the heavy weight kit for shooting overpressure ammo suppressed. Even with the extra weight, the Guard is smooth shooter. With light bullets and recoil parts it will be the go to gun for competition shooting with rimfire-like recoil.

Rifle, MkGs DRB2, 9mm

  • Barrel: 16-inch 4140
  • Caliber: 9mm Luger
  • Muzzle device: CMMG SV Brake 1/2-36
  • Handguard: CMMG RKM14
  • Upper: Forged 7075-T6
  • Lower Billet 7075-T6
  • Trigger: Geissele Automatics SSA
  • Capacity: 33 rounds with Glock magazine
  • Weight: 6.2 pounds unloaded
  • Length: 32.5 inches
  • MSRP: $1,599

While the Guard costs more than its base line competitors, it delivers high performance. The Magpul stock, CMMG muzzle brake and Geissele Automatics SSA trigger make it shoot like a dream.  These features taken together make the Guard great for competition or self-defense. You don’t need to accessorize the Guard, it’s complete right out of the box.

I was an earlier adopter of pistol caliber carbines such as the Colt SMG, the MP5 and the Ruger Police Carbine. The Guard is a mature design. The Colt pattern mags used by other guns had more than their share of problems. The Guard ran great with Glock factory magazines of all capacities and functioned well with most aftermarket magazines as well.

KCI 50 round drums and 33 round stick magazines really shined. Extended magazines are fun when they work. The Guard loved them.

Some Pistol Caliber Carbines are funny about hollow point ammo. This is a significant issue if you are considering one for home defense. After testing it with a wide variety of ammo, I would not hesitate to use the Guard for protection.

I shot the following ammunition with no issue:

  • Armscor 115-grain full metal jacket
  • Freedom Munitions Hush 165-grain round nose
  • Liberty Amunition Civil Trainer 65-grain frangible
  • Polycase 80-grain round nose
  • Speer Gold Dot 115-grain jacketed hollow point
  • Speer Gold Dot 124-grain jacketed hollow point
  • Sig Elite V-Crown 115-grain jacketed hollow point
  • Sig Elite V-Crown 124-grain jacketed hollow point
  • Sig Elite V-Crown 147-grain jacketed hollow point
  • Winchester Black Talon 147-grain jacketed hollow point

I have to admit, this gun surprised me. I started with “I wonder if it will shoot these hollow points” and in short time thinking “There’s no way it will cycle these 65-grain rounds.”  The Guard rose to the challenge.  A special thanks to Armscor International for providing most of the ammunition for my test.

The Guard is ultra-reliable. I fired over 4,000 rounds of varied 9mm from our test gun with no cleaning.  It ran everything we fed it. It has since fired another 1000 rounds. Accuracy? While not designed for long range, we were shooting stationary skeet at 100 yards and ringing steel at 200 yards.

I tried several different sights, but most of the shooting was done with my faithful old Trijicon Reflex Sight. Taking a head sized target at 25 yards is simple with the guard. Shooting 3 inch groups standing unsupported was also easy. At 50 and 100 yards there were a couple of inches of drop and the groups grew to 6 inches. With magnified optics and good ammo you could get effective groups at 200 yards.

I spent most of my time shooting an 8-inch plate from Complete Target Solutions. Even at 100 yards, it was easy to see and hear the hits and there weren’t many misses. Even with the wide variety of ammunition, the Guard is so accurate and easy to shoot that you had to mess up pretty hard to miss.

You can do drills with dueling trees, plate racks, Texas Stars and other targets that would not be safe to shoot with rifle calibers and boy is it fun. One thing you quickly figure out shooting the same drills with handgun and a pistol-caliber carbine is how much faster the carbine is. On most drills the time is cut in half. This translates directly into the real world. The CTS steel targets took most of the 5000 rounds from 10 to 50 yards with no wear and tear.

With the included Geissele Automatics SSA trigger, I was able to get .15 second splits while staying on target at 25 yards repeatedly. The gun has low felt recoil even with overpressure loads. It handles well and shoots fast. I was a little worried that people hearing my shots on the next range over would think I had a machinegun, but I was having so much fun I couldn’t stop. When 5 or 6 rounds hit steel .15 seconds apart it is pretty cool.

CMMG began in central Missouri in 2002 with a group of knowledgeable and passionate shooters committed to quality and service. They have built a reputation on attention to detail, innovation and the superior craftsmanship. They make high quality AR rifles in America and source all their own parts.

CMMG developed Radial Delayed Blowback to handle .45 ACP, the first caliber introduced in the Guard series.  The recoil impulse of .45 ACP didn’t lend itself to merely adding additional weight to the carrier and buffer, it needed something different.

The Guard is covered by CMMG’s Lifetime Quality Guarantee. CMMG, Inc. will repair, replace or substitute parts at no charge to the customer if a defect of material or workmanship is found.

The Guard does everything well and the quality is among the best in the industry. It is fun and effective in any role. Over the years, I have shot most every rifle shaped platform that chambers 9mm. Whatever your application, the Guard in is a great option. I would not hesitate to use the Guard for home defense, in a pistol-caliber carbine competition or as a plinker to train AR skills at 9mm prices. And a 124gr jacketed hollow point from a 16 inch barrel will have all the energy transfer you need for urban predators.

Get your very own Guard HERE on!

About the author: Mark Miller is a former Customs Agent and a Green Beret who served in Afghanistan and a number of other live fire locations. A student of firearms and shooting, he is an FFL and a SOT. The guiding philosophy of his life is that terrain and situation dictate tactics and the enemy always gets a vote on any plan.

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  • dwhack August 15, 2018, 3:04 pm

    Hey, Mark!
    Sorry to be a little off topic, but I noticed the rig you had stacked behind the PCC. Can you share who makes the plate carrier/mag holders? Just curious.

    • Mark Miller October 6, 2018, 9:53 pm

      Body Armor & Ballistic Plates by Premier Body Armor, ammo pouches from

  • marty davis August 14, 2018, 3:13 pm

    I’ll take my HK 94 anyday (1986 for $550)

    • Mark Miller October 6, 2018, 10:17 pm

      Nothing wrong with the reliability of the HK94, KCI USA now makes great affordable magazines for it. The ergonomics, not so great. Can you manipulate the safety from a firing grip? Sights? not very precise.Adding optics? a little dicey. Last round bolt hold open? not so much. Reloading? Make sure you have time to lock the bolt to the rear, remove the magazine, put in a new mag and release the bolt.

  • John Bibb August 13, 2018, 12:12 pm

    Seems a tad pricey to me! High Standard prices similar pistol cartridge rifles for around $400 bucks.
    You can buy an El Primo .30 cal. M-1 Carbine clone for this money. Or 2 far less pricey Auto Ordinance clones instead. With 200 yard effective range and a folding stock also. With Hornady’s excellent FTX expanding bullets—far higher velocity and about double the muzzle energy of this carbine. With a 5.5 pound weight also.
    John Bibb

  • Norm August 13, 2018, 11:51 am

    $1600 for a pistol caliber carbine? Looks like a nice piece, and your review is good, but a dispassionate look at return for the money, it just seems to be way out of consideration for me.

  • Richard Stern August 13, 2018, 9:12 am

    Call me a Grammar Nazi – but MUZZLE BRAKE – not break. The purpose of BRAKES (versus flash hiders), is to slow down/mitigate recoil, by diverting gases to the rear to offset (BRAKE) recoil. Kinda grating – like calling mags, clips.

    That aside – it’s an interesting piece.

    Still more impressed with my Sig MPX, to the point where – most folks want a SHORTER BARREL, but I want a LONGER ONE on it. Carbine conversion (not really 100% legal for something sold/registered as a pistol, but as long as I don’t shoulder the brace – right?), will increase velocity (and accuracy) on the +P 124gr ammo I run, making a more effective firearm for mid-range encounters (25-100 yards).

    Lots of 9mm carbine/rifles hitting the market. From a SHTF perspective, considering re-arming tactics (that is, grabbing ammo from an enemy out in the field, versus RTB to re-arm) it’s a good caliber to run as a rifle, despite it’s more limited effective range. I got the 9mm kit for my Tavor (found one on sale at a “couldn’t resist price”), but I don’t see issues re-arming with .223/5.56 (versus .308/7.62×51) – and at this point 9mm isn’t that much less expensive than .223 (+/- $.10 a round in bulk), so stocking up on either caliber isn’t going to put anyone on an EBT card.

    Normal mag capacity in carbine form, is not an equalizer (as it is in pistol form – 9mm being higher capacity then .40/.45). 30 rounds of 5.56 shoots just as easy as 9mm, and is more effective at greater distances.

    As an “urban predator” tasking, good choice – and, if I didn’t have other options already in the rack – I’d consider this piece. CMMG makes nice stuff – and you could probably stick a Franklin Binary in this, and make it even more formidable (run one in my MPX, it’s a hoot to shoot, and rate-of-fire doesn’t reduce accuracy like a bump-stock).


  • Merlin August 13, 2018, 9:08 am

    Sounds great, but a prohibitive price knocks it out of contention for me.

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