The 9mm GUARD from CMMG is an AR-15 pistol caliber carbine (PCC). Not just another Colt clone, the GUARD uses CMMG’s patent pending Radial Delayed Blowback system and is fed from Glock 33 round magazines. The Guard has fully functional AR-15 controls, including last round bolt hold open. The 9mm Guard is available in six models including pistols.

I have had my 9mm Guard for six weeks now and I have fired over 3000 rounds of varied ammunition. The only malfunctions I have had were magazine induced. I was an earlier adopter of the pistol caliber carbine starting with the Colt SMG, MP-5 and the Ruger Police Carbines. The Guard is a mature design which shoots like AR. 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 (surprisingly) functioned well with most aftermarket magazines as well.

Magazines are important and already having a bunch of Glock mags made the Guard more desirable. I partnered with my buddy and fellow writer Graham Baates for one range day. Not only does he have guns nobody wants, he has a box of misfit aftermarket “glock type” magazines and a lot of random 9mm ammunition. He generously allowed me to shoot with his stuff…a lot.

We spent most of the time shooting an 8 inch CTS plate target . 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.

Part of what people love about Glock mags is their reliability, but not all aftermarket “Glock” mags are created equal. We tried an old Korean 33 round mag, a new Korean mag (which I really liked), a Jagemann mag and an ETS mag. They all ran great with a variety of ammunition. The ProMag didn’t feed well but to be fair, it didn’t run well in a Glock handgun either.

Some Pistol Caliber Carbines are funny about hollow point ammo. This is a significant issue if you are considering using a PCC for home defense. I would not hesitate to use the Guard around the house. Thirty-three rounds on 9MM JHP should solve most domestic issues, the sight of that giant magazine alone should have a certain calming effect on most would be criminals.

We shoot the following with no issue:

115gr Armscor RH

147gr Winchester  Black Talon JHP

124gr and 115gr CCI Speer Gold Dot JHP

115 gr Sig Elite Ball RN

115gr Sig Elite V-Crown JHP

124gr Sig Elite V-Crown JHP

147gr Sig Elite V-Crown JHP


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165gr Freedom Munitions Hush

80gr Polycase RNP

65gr Liberty Civil Trainer


I have to admit, this surprised us both. It started with “I wonder if it will shoot these hollow points” and rapidly degraded to “no way it will cycle these 65gr rounds.”  Challenge accepted.  I used the optional buffer kit with the heaviest weight. A special thanks to Armscor Ammunition for providing most of the ammunition for my test.

Many current AR PCCs (even the expensive ones) lack a bolt hold open. This slows your reloads and conflicts with habits formed shooting conventional ARs. The Guard has a full functional last round open with a dual-pinned, fully machined bolt catch linkage, using a standard bolt catch spring. It works every time.

My Guard is Cerakoted in an optional Burnt Bronze finish.  I added the buffer weight kit because I wanted to shoot +P ammo and hang a suppressor on it. Even with the extra mass, the Guard is smooth shooter. If you shoot light bullets and tune the bolt weight, it will be the go to gun in competition with .22 like recoil.

Over the years, I have shot most every rifle shaped platform that chambers 9mm. What ever your application, the GUARD in 9mm is a great option. I would not hesitate to use the Guard for home defense, PCC competition, or as a plinker to train AR skills at 9mm prices. A 124gr jacketed hollow point from a 16 inch barrel will have all the energy transfer you need for urban predators. With a 33 round magazine, repeat as necessary.

One huge training benefit of the PCC is shooting pistol steel. You can do drills with plate racks, Texas Stars and other targets that rifle caliber safety would never allow and boy is it fun. Something you quickly figure out when you shoot the  same drills with handgun then a PCC is how much faster the PCC is. On most drills the time is cut in half. This translates directly into the real world. My CTS steel targets took most of this 3000 rounds from 10 to 50 yards with no wear and tear.

Precision is also a benefit. Taking a head sized target at 25 yards is simple with the Guard. I was regularly shooting 3 inch groups standing unsupported. At 50 and 100 yards there was a couple of inches of drop and the groups grew to 6 inches. I am sure with magnified optics and good ammo you could get small groups at 200 yards.

With the Geissele Automatics SSA trigger which came with my Guard, I was able to get .15 second splits while staying on target at 25 yards on demand. The gun has low felt recoil even with +P 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.

The big news here is the GUARD’s Radial Delayed Blowback system. The bolt carrier group (BCG) that looks like those found on a regular AR-15 but with a different operation. Simple and elegant, the bolt key is forced to rotate and unlock slowing down the BCG just enough to safely cycle 9mm while simultaneously keeping the BCG and buffer lighter than Colt pattern 9mm AR15s reducing felt recoil.

CMMG developed the Radial Delayed Blowback to handle .45 ACP, the first caliber introduced in the GUARD platform.  The recoil impulse of .45 ACP didn’t lend itself to merely adding additional weight to the carrier and buffer. While it appears to have a standard AR15 bolt carrier group, the Guard bolt is different in some important ways. . The bolt key doesn’t pass gas, it is there to grab the charging handle. As blowback pressure pushes, it unlocks the bolt, delaying opening just enough to allow the bolt to reliably cycle.

In a 9mm straight blowback system, only the weight of the bolt and buffer mitigate the recoil impulse, the Guard bolt and buffer weight are much lighter which means less felt recoil as those masses move. The combined difference in weight of the bolt carrier group and buffer when comparing straight blowback versus Radial Delayed Blowback can be as much as 6.5 ounces.There is an Action Tuning Kit (bolt weight set), sold separately, which allows the user to change the weight of the bolt to precisely match the recoil impulse. This is going to come in handy for suppressor users and short barreled pistols.

The MkGs GUARD comes with one 33-round factory Glock magazine. Bolt weight kits will be sold separately for those who wish to fine-tune the GUARD for suppressor usage.

Rifle, MkGs DRB2, 9mm
PART#: 99AE67B
BARREL: 16″ M4 4140CM SBN, 9mm
MUZZLE: CMMG SV Brake, Threaded ½-36
FURNITURE: Magpul MOE Pistol Grip, Magpul CTR stock with 6-pos mil-spec receiver extension
RECEIVERS: Billet 7075-T6 AL Lower, Forged 7075-T6 AL Upper
TRIGGER: Geissele Automatics SSA
MAGAZINE: Glock 9mm 33 round
MSRP: $1,599.95

I really like this gun and will be using it at home and for competition. It does everything well and the quality is among the best in the industry. It is fun and effective in any role.

Get can your very own Guard HERE

CMMG Lifetime Quality Guarantee
CMMG, Inc. will guarantee its products against defects in material or workmanship.  CMMG, Inc. will repair, replace or substitute part(s) (at CMMG, Inc. discretion) at no charge to the customer if a defect of material or workmanship is found. All service work must be carried out by CMMG, Inc.


Featured Photo: Premier Body Armor Plate CarrierWilder Tactical Magazine PouchesArmscor Ammunition and Korean no name gun show “glock type” generic  magazines.

This article is courtesy of The Loadout Room.