An AR-Based Grease Gun? CMMG’s New MkG45 Guard Carbine – NRA 2017

The CMMG Guard line of .45 ACP carbines give shooters an AR-based carbine in this big-bore pistol cartridge.

Do you want a modern-day “Grease Gun” .45 ACP carbine (semi-auto, of course) that is based off the AR and feeds from Glock magazines? Then CMMG has you covered with the new MkG45 Guard series.

Released at the 2017 NRA Show in Atlanta, Georgia, the Guard (which is offered in five different configurations) employs a patent-pending “Radial Delayed Blowback” system and feeds from .45 ACP-sized Glock magazines. CMMG tested out traditional straight blowback systems as well direct gas impingement systems, but issues with reliability sent them back to the drawing the board.

The Guard employs a Radial Blowback System that uses a rotating bolt that prevents the action from opening until pressure drops to safe levels. Image courtesy of manufacturer.

What resulted was the Radial Delayed Blowback System that interestingly employs a rotating bolt that requires the force of recoil to rotate and unlock, keeping the action closed long enough to allow chamber pressure to drop to safe levels. The result is a blowback system that does not require a heavy and large bolt carrier system (reminiscent of the HK-style roller-locked systems) and offers a lighter carbine with reduced recoil. The best of both worlds, huh?

The Guard is offered in pistol, rifle (top) and SBR (bottom) variations.

Each Guard comes with one 13-round factory Glock 21 magazine, and bolt weight kits will be offered that allow shooters to fine-tune the system for use with +P ammo or with a suppressor.

Anyone familiar with an AR will be right at home with the .45 ACP Guard. Shown with extended magazine.

The MkG45 GUARD comes with one 13-round factory Glock 21 magazine. For optimal reliability, CMMG recommends using factory double-stack GLOCK .45 ACP magazines. Bolt weight kits will be sold separately for those who wish to fine-tune the GUARD for +P ammunition or suppressor usage. The Guard is offered in carbine, SBR and pistol variants.

Keep an eye out for a full review in the coming weeks.

For more information, visit

{ 31 comments… add one }
  • Scotty Gunn May 9, 2017, 6:59 pm

    Interesting. Now do one in 10mm.

  • Russ H May 8, 2017, 9:05 pm

    No offense but I don’t get AR’s in pistol calibers – 5.56, 300 BLK, and 7.62×39 yes, 9mm or 45, no. I know there are plenty of folks who are into this sort of thing (some are friends of mine) who have 9mm AR’s or Scorpion and HK SP5K or SIG MOX semi auto variants who love them. If they were full auto I’d get it but in semi they are an overpriced, heavy pistol (to me). If you like it – enjoy it! I love most all guns but I just can’t wrap my head around pistol cal AR’s. If someone gave me one I’d keep it but I wouldn’t buy one. I do have a couple AR pistols in 5.56 that some people think are idiotic but I like them, well one (the 7.5″ is about to be rebarreled with a 16″ upper). I do have seven AR’s (one is an AR10 type) that I built so I’ve tried to expand my horizons (they’re all different in some manner) so maybe one day I’ll build a 9mm. Again, I’m not being critical of this weapon or those who like them – it’s just not my thing for some reason. And what’s up with the “grease gun” reference? I was expecting to see something resembling a grease gun.

    • Edgar May 10, 2017, 3:27 pm

      Whats not to get? Its another gun. You and I and most everyone else enjoys shooting sports and exercising our 2nd amendment rights. When I have enough AR\’s and Ak\’s…well the next variant is the AR in a pistol caliber. A 5.56mm pistol is a great piece but it does not handle like a pistol caliber AR. Pistol Caliber AR\’s are FUN to shoot and although they lack the power of rifle caliber ammunition, they are still more than capable of performing very well for defensive use if called upon. Of course if I had to choose which one to take to battle, I would choose the larger caliber. Pistol Caliber AR\’s are not for battle. They are for fun, competition, training, practice and much more. They fill those roles well and less expensive than full size rifle AR\’s. They are more than capable of performing any defensive or offensive task. So whats not to get? You already have seven AR\’s. Certainly you have a big enough safe to squeeze in one more AR. Get yourself one to go with the other seven. As an avid shooter I completely understand you owning so many AR\’s. Great thing is that we don\’t need an excuse to buy more of them. I was thrilled when I finally got mine complete. Get yourself one and get that feeling again… will put a smile on your face.

  • docduracoat May 8, 2017, 3:00 pm

    It’s an AR in .45 caliber
    It is NOT a grease gun!
    Or a Thompson
    AR’s in 9 mm have some popularity
    An AR pistol in .45 with a Sig brace would give the CZ Scorpion Evo 9mm some competition

  • wrangler5 May 8, 2017, 2:53 pm

    Marlin Camp Carbines go for almost this much today, largely because they haven’t been made in decades and people still want one. But if Marlin fired up that line again, and especially if they modified the design to use a commonly available magazine, I’ll bet the retail price on one would be down to half or even a third of this CMMG “tactical” version.

  • Joe May 8, 2017, 12:24 pm

    I watched a video of a hunter taking out a 250 pound class tusker hog with a .45 ACP pistol once. It took all seven rounds and the porker dropped finally within five yards of the hunter who swore to never take a pistol to a hog fight again unless it was .44 mag or better. Nice toy but give me an AR with a punch not a tickle.

    • sargintrock December 22, 2017, 10:18 am

      I must admit when I saw the picture of that Hogzilla killed by a taxidermist in his front yard in Georgia with his household .38, I was surprised! Shot placement is Everything!

  • mf May 8, 2017, 12:16 pm

    good for slide fire or bumpsky use

  • Tim Mornard May 8, 2017, 11:45 am

    So… they’ve been able to re-engineer the Hi-Point $300 carbine into a $1300 gun… that’s pretty impressive…

    • john roper December 22, 2017, 9:21 am


    • Franco Hensley December 23, 2017, 5:37 pm

      I have a Pair of Hi-Point weapons and although they ain’t pretty, they do a lot of work and no complaints from this owner.
      Why buy a pretty toy when an ugly one works? The High Point .45 Carbine is a lot of fun!

  • Aydene May 8, 2017, 11:00 am

    The 45 is a classic cartridge, readily available, and I would imagine many folks have a bunch laying around that they use in their Colt, or reasonable repro, 45 acp auto. Not the only point to consider. As far as an argument over mags, “mags is mags,” Cripes the market is full there too, one copies another and yadduh – dadduh. I have revolvers that fire 45 acp and 45L, two 45acp autos, and frankly I think a 45acp rifle is an OK member joining the family. 45Ls have been bouncing out of lever action bbl.’s like forever.

  • singleshotcajun May 8, 2017, 10:56 am

    I would like to see more information on the design of this radial delayed blow back. Always interested in new ways of doing things.

  • Joseph R Petrik May 8, 2017, 10:51 am

    Ah, why not just buy a Thompson ??!!

    • ScottGunn May 8, 2017, 9:33 pm

      Problem with the Thompson is the recoil and jamming issues. If you want the best 45 subgun get an HK UMP 45 or conversion. I’ve fired both in semi and full auto, and own an UMP. Super lightweight, rugged, very very accurate and the lack of recoil is amazing. Only negative is that they aren’t cheap or easy to find.

    • Edgar May 10, 2017, 3:32 pm

      Thompson…..HEAVY ! especially if you are carrying it around the field.

  • Cyrus May 8, 2017, 7:22 am

    This falls under the “Who Cares” Category!

    • Aydene May 8, 2017, 11:01 am


  • Rich W. May 8, 2017, 6:29 am

    I’d rather have one in .40S&W or 10mm.

    • Samuel BENNETT May 9, 2017, 8:32 am

      Yeah: a ten mm would be great have you ever fired the forty five super. That a bad boy. But the ten mm is awesome. I’ve carried a glock twenty since 91 live only had one jam and that was with fpb two hundred grain. The 175 grain sth is the best hot factory round I’ve found and they do 720 lbs at p blank. Not to bad. But I agree a ten in an Ar would be great. But the mag capacity. Suck’s on the Olympic arm’s version. With a kriss mag extended 25 pretty good. That would be a bad boy in an ar version. SRB69

  • DC May 8, 2017, 5:35 am

    Um whats the price lol

    • Blasted Cap May 8, 2017, 7:05 am

      Went to their site with the same question. Rifles start at $1299. Yikes.

  • Jay May 8, 2017, 4:21 am

    Anent Glock magazines, they are metal lined and as durable and functional as any all metal magazine. They don’t look as good granted but there’s nothing especially eye appealing about any AR as far as I’m concerned. Seven years of M16A1 totally soured me on anything AR.
    But, having also toted a grease gun about a time or two as well, I don’t see any compare and think it a poor choice of terms. First of all, the “grease gun” wellllll… looked like one! It was a heavy little beast, dirt cheap and looked like it too. I mean, sticking your finger in a hole in the bolt to draw it back?! I say it takes more than a commonality of cartridge to make something to compare.

    • Mark Timblin May 9, 2017, 3:34 pm

      I carried the M16A1 w/M203 grenade launcher for 16 years woulda been 20+ but a little thing called Dessert Storm a barracks full of Reservists while my own Reserve unit was 800 meters away. I was 400 or so meters away when that damn scud hit….amazing I made it though. That being said, I never had an issue with the A1 except with the M203 attached it was a heavy bastard, it was a heavy bastard even without the M203 attached, 30 round mag full, those who were in back when know that we didn’t have the fancy 1 point slings on bungees. Of course that wouldn’t have worked with the 24″ or 26″ barrel on the damn beastie. Wasn’t so bad when I was active duty with the A1/M203 combo I had access to new slings etc. I needed anything for my weapon go to the armorer and/or supply daddy and get what I needed. Same with my 1911, actually was able to gt almost all new parts for both my A1 and 1911 whenever range time came up I consistently shot expert with everything I was allowed to qualify with. The grease gun, was an abomination, damn thing would rise up when you held down on the trigger. As a track wheeled vehicle mech my first hitch the grease gun was originally designed for tankers and some airborne troops. Nice thing about the grease gun it was cheap, it was easy to repair, even in the field one could often do repairs that would last until you got to supply and got it repaired by the company armorer.I could do OK never made better than sharpshooter with the grease gun, which a lot of folks found interesting. I liked the grease gun well enough, hive me my A1/M203 combo, even now with all manner of weapons on the market I have my AR15 with a quad rail system forward grip, flashlight & laser, optics consist of an EOTEC clone and a 3X magnifer. Have a decent 1 point sling 6 position stock only thing I don’t have is the 40 mm grenade launcher. I understand there is a 37 mm launcher that is damn near identical to the 203, might be worth looking into, only thing from my understanding about all you can get ammo wise are some flare type grenades, paint rounds, possibly some LEO grenade ammo. I dunno I’m gettin too damn old and too messed up to be fartin around with all that. Being retired LEO I could talk with some “friends” see what is available and go from there, something to consider, only for a SHTF scenario. Peace….through superior firepower. If you can read this thank a teacher. If you can read this in English, thank a veteran.

      • Greg Hawkins May 14, 2017, 9:30 am

        Thank you for your service soldier.

      • Franco Hensley December 23, 2017, 6:05 pm

        I never trusted the M16 in any version. Feed jams, dirt, mud and just poor craftsmanship or assembly gave me a reasons to carry the best ever jungle weapon, the M14E2, through both of my tours in Vietnam. The .308 round would cut through vegetation much further than the light-weight .223. Triple canopy needed a heavy round, not a ‘Matty Matel’ special. Shooting at a Banyan root system needed the .308 from my M14 or the M60. Some grunts liked carrying lots of rounds, however when you shoot semi-auto, you tend to aim instead of the “spray & pray” method. The M14 was heavy for some, but that wood stock, bi-pod and full-auto switch made it a power house in the bush. The M203 in heavy jungle was a waste. Fighting was often within 25 meters and you didn’t have time to load that tube more than once. There is nothing more frightful than the sound of the M14 or M60 on full auto. Heavy weapon, heavy rounds = job done. For you Desert Grunts, the M203 was useful and you had time to load if it was clean. I guess it all depends on how much distance you have between you and danger. I’d like to know how many rounds a minute someone could actually fire with the M203. And did you rely on your .223 rounds more often than not? I once saw a M79 gunner put 15 rounds down range in less than a minute firing one-handed and loading with the other. I imagine he had a lot of practice. M16A1/M203 vs. M14E2 & M79. I would take the two guys verses one guy trying to do both jobs. What were they thinking?

        If you have close-distance fighting, an AA-12 is just what you need! Grenades too! No one wants to face a 12 gauge!

        For every Grunt, past and present, have a Blessed Christmas and a Very Happy New Year.

  • Derp May 8, 2017, 3:01 am

    Glock mags are metal with a plastic coating…

  • American May 1, 2017, 8:16 pm

    A Glock magazine ? What about a metal; magazine option ? or a Pro Mag ? How about a M-3 magazine ?

  • American May 1, 2017, 8:15 pm

    Plastic GLOCK magazines ? No Thanks ! What about a metal magazine option, like M-3 or Thompson . There are plenty available.

    • Cody May 8, 2017, 8:14 am

      M3 Grease gun magazines are up to over $50 a pop if you can find them. They are definitely not “available”. Keep Shooting tries to stock them at $30 but they sell out very quickly. I can’t tell you the last time I walked into any store and saw a magazine for a Thompson. Glock mags work and are readily available. I’m confused though…Since when do magazines have to me made of metal to work? The CZ Scorpion and the HK UMP both utilize polymer mags and both are proven platforms. Both are polymer guns too, but oh no, must be junk. I feel sorry for your narrow view on plastics and polymers. You really limit yourself to better materials and improving technology.

      • Samuel BENNETT May 9, 2017, 8:42 am

        Yeah; Bro Glock mag’s are very dependable and don’t rust earthier. It’s according to the gun mfg standard’s on mag material usually but pistol mag’s. Go to Glock hand’s down in my opinion. Happy shooting in whatever mag you choose.SRB69.

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