TFBTV: CMMG Mk-W “Anvil” .458 SOCOM AR15 Overview:

As previously reported, CMMG sent James a pre-production model of the CMMG Anvil for review. James took the Anvil out on several range trips over a month-long period and fired around fifteen boxes of various ammunition through the Anvil without any cleaning. In this overview, James discusses what the Anvil is, how it was engineered, and tries to answer the question “why .458 SOCOM?” Enjoy the review.

Please subscribe!!! Click here.

Please subscribe!!! Click here.

Thanks to our sponsor Ventura Munitions. Without them TFBTV Would not be possible.


Transcript …

– Hey guys, James again for TFB TV.

Today on TFB TV I’ve got a little bit of an odd bird for you.

It’s the CMMG Mark W.

I know what you’re thinking.

Does Mark W stand for Mark Wahlberg? Unfortunately, no, it does not.

This not an homage to Markie-Mark.

It’s an AR-15 in 458 SOCOM.

Now the guys at CMMG just called this thing the Anvil, and I can see why because this thing, it’s solid as a rock and it is a bruiser.

458 SOCOM is a powerful round and this is just as powerful a gun behind it.

This CMMG is custom-built from the ground up.

CMMG engineered it and as you’ll see later in the video I actually interviewed one of CMMG’s engineers, one of the guys who was behind the manufacture and the design of this gun.

Now, going from the front to the back you can see the front’s got a muzzle-brake to help with the recoil of that 458 SOCOM, it’s got a free-float CMMG KeyMod handguard that goes all the way, almost the entire length of the 16-inch barrel, KeyMod and three, six and nine o’clock running the full length of the handguard.

You may notice here this has got a Lancer, what looks like a Lancer.223 magazine, it even says 5.56 by 45mm in the mag well, but at the very top where the follower is, it says 458 SOCOM.

Now, while 458 SOCOM will work in any 5.56.223 STANAG AR-15 magazine, 5.56 45mm PMAG.

CMMG has manufactured, collaborated with Lancer to manufacture these magazines that are optimized for 458 SOCOM.

It also comes with a Magpul MOE grip, a Magpul CTR stock, standard charging handle, standard safety selector, standard mag release, standard bolt catch and bolt release, Billet Lower, gorgeous Billet Lowers, an AR-10 Lower, based on the AR-10, however the mag well is slightly different to accommodate the AR-15 profile magazine.

There’s also a few other improvements in the Lower that I can talk about a little bit later.

The mag well is also beveled since you have all that extra space.

It’s beveled and flared, so easy insert for these magazines.

This thing just reeks of CMMG, which means it is quality from front to back, it feels like a great gun, handles well, I’ve shot it already, and it handles the 458 SOCOM round beautifully, even though the 458, there’s no way around it, it’s kind of a bruiser.

So that really raises the question why did CMMG make, from the ground up, a 458 SOCOM-dedicated AR? Now, as I said I interviewed CMMG’s engineers, and they say one of the primary reasons was the versatility of the 458 SOCOM round.

– [Voiceover] On the 458 we liked it because it’s very versatile, and it’s projectiles ranging from 140 grains around 3000 feet per second to 600 grain at around 1000. So you got super and sub-sonic.

There’s just a lot of–a lot of innovation that you can’t really pack into a 5.56.

So, with all of that on top of that ballistic energy that it creates it’s, to me, and to the owners and the people who get to decide which projects we do, it is a very awesome round.

Most people are wondering is that 458 worth the trade-off with the reduced capacity and the cost and what-not, and my answer to that, and I believe a lot of people, it’s entirely dependent on what you’re wanting to do with the rifle.

I would not go up against a 600-pound hog with a 5.56.

So it depends, if you’re looking to go against big game, and you want to be able to knock it down, the Anvil, with the 458 SOCOM is gonna be your rifle.

– [James] So CMMG really wants to emphasize that not only is ammo available but a lot of different types of ammo are available, and they’re all built for their own distinct purposes.

So that again goes back to the versatility of the round.

On the left-hand side is the Black Butterfly 300 grain ballistic tip.

On the right-hand side is the Black Butterfly 350 grain flat nose.

This is the Corbon DPX Deep Penetrating Expanding round, 300 grains, 1900 feet per second velocity.

Here’s the Underwood Expander, which is a 300 grain round that reaches almost 1900 feet per second in velocity.

This round is a funny one.

This is the 140 grain, Polycase ARX Inceptor.

– [Von] I don’t know the specifics completely but due to the Polycase, the way they designed it, it actually spins, so it’s travelling at 3000 feet per second but the way it spins and the way it’s designed, it multiplies the fluid that spins off of it at three times whatever it’s traveling, so when it goes into a wound it’s like throwing, you know, whatever it’s throwing out at like 9000 feet per second.

– As far as defense guns go, it’s gonna be hard to swing me over to 458 SOCOM coming from 5.56 or.223 in the AR-15, the standard chambering.

And that’s because the 458 SOCOM is really expensive, as I said the recoil is brutal but of course, the trade-off is you get a ton of power and a lot of versatility with the rounds, but, one of the biggest considerations for me is this, which would otherwise be a 30-round magazine for 5.56 will hold 9, 10 or 11 458 SOCOM rounds.

So you’re basically cutting your capacity by a third.

But again, CMMG is primarily targeting this rifle towards hunters and that’s something that it’s going to do very well at, especially with the adaptability of the 458 SOCOM to differing circumstances.

But let’s go over the specs real quick before I take it to the range again.

There are three variations of the Anvil right now, there’s the standard Anvil-T which is $1850, the Anvil-XBE which adds Magpul furniture and ups the price to $1950.

And then the XBE-2 which add a Magpul furniture and a Geissele two-stage trigger.

The XBE-2 with the two-stage trigger is $2149.

The one I shot today is the XBE and it has an MSRP of $1949.

Barrel has a one in fourteen inch twist, some medium taper, a 416 stainless steel barrel.

It comes with a CMMG SV muzzle brake.

The barrel is threaded five-eighths by 32.

Billet, upper and lower 7075 T6 aluminum receivers.

The XBE has the single stage mil spec trigger, but again you can go to the XBE-2 and get the Geissele.

It comes with the MOE pistol grip.

CTR carbine stock.

It weighs seven and a half pounds unloaded.

It is 33 and a half inches collapsed, and has an MSRP of $1949.

CMMG says that using a large diameter caliber like 458 SOCOM with a standard 5.56 bolt would require a lot of material to be milled out the standard 5.56 bolt face in order to function, which would make it thin and fragile, so the power bolt using the larger bolt face is a little bit more robust than using a milled-out 5.56 bolt face, which makes a lotta sense to reduce the weight, and although the frame is based on the AR-10 the mag well accepts an AR-15 magazine.

And one thing really cool perk is that it uses the SLR Rifleworks Sentry 7 Adjustable Gas Block, so you can click-adjust the gas block to work with varying loads of 458 SOCOM.

So as long as I’ve been shooting I have never fired 458 SOCOM.

This is gonna be a first for me.

Let’s see how this monster of a round shoots out of this platform.

Good lord.

Good lord.

That is a bruiser of a round.


Whoo! God, I gotta tell you guys, that has a shitload of recoil.

I try not to complain, but that is holy shit.

That is a lotta kick.

Now you guys that are getting 458 SOCOM, you’re getting it for a reason.

You know what you’re getting into.

It’s got a lotta kick because it’s got a lot of power.

There’s a lot under the hood.

You’re talkin’ about, 2000 feet per second, 300 grain, like.44 Magnum size bullets, screaming out at 2000 feet per second.

That’s pretty damn impressive, but what’s gonna happen? You’re gonna have some recoil.

What else is gonna happen? You’re gonna be severely limited in terms of your magazine capacity.

This is a 30-round magazine if you jam 5.56 into it, but once you start using 458 SOCOM you get 10.

All right so I’m gonna try some different ammo types here.

The top five rounds in this magazine are the Black Butterfly 350 grain flat nose rounds, the bottom five rounds are going to be the Black Butterfly ballistic tip 300 grain.

Let me see if I can tell a difference at least in terms of recoil.


Those 300 grains definitely had a little more ummph to ’em.

Um, so, all other things being equal, if you’re trying to decide between the two of them and recoil’s a factor to you I would definitely go for the heavier rounds rather than the lighter.

But you know, this thing’s working wonderfully.

Uh, everything works on it.

Looks good, works well.

Try a few more different types of ammo.

All right now I’ve got the 140 grain Polycase.

Man! That’s very little recoil for a 458 SOCOM round.

Wow, I don’t know why that is.

But, can’t explain it to you but I can tell you that the 140 grain Polycase, very easy in terms of recoil.

Man, I’m telling you guys, I really like this 140 grain, the Polycase 140 grain.

Very pleasant.

I don’t know what it does, if anything.

But it does have light recoil.

Pretty nice.

Now I know I’m gonna regret it, but let me go ahead and let five or six of these just rip and see what happens.


(quickly exhales) Wooo! God! Ahh, man.

That’s nuts.

So, final thoughts on the CMMG 458 SOCOM.

You’re getting a CMMG AR-15 in 458 SOCOM.

That’s all that really needs to be said about the rifle itself.

Fit and finish is excellent, I love the free-float handguard, I love the Magpul factory furniture that it comes with, it’s a nice AR platform gun, and it’s in 458 SOCOM, so if you’re interested in the 458 SOCOM, great, look at CMMG.

I guess the bigger issue is the fact that this gun is chambered in 458 SOCOM.

Now I think it’s fantastic when manufacturers like CMMG offer support to what were previously regarded as wildcat calibers, and a lot of you out there, I’ll bet 90% of you watching this video have never handled a 458 SOCOM, fired one, I know I hadn’t until I made this video.

But then the other 10% out there are probably ecstatic, giddy that you’re gonna be able to find this monster of a caliber in a mainstream-produced AR-15 like the CMMG Anvil.

So the bottom line is this is an excellent AR that just happens to be chambered in a semi-obscure round.

Am I gonna buy this gun? Probably not.

Are you gonna buy this gun? Probably not.

However CMMG knows that and they have marketed this towards a sub-set of shooters who are going to welcome it with open arms, as they should, because CMMG did a great job with this rifle, and they’ve done a great job getting third party support for 458 SOCOM ammunition, making sure that you can find the load that you want, and really, ammo availability is very important if you want a platform like this to take off.

So, all in all, great job again CMMG, thanks for sending me this pre-production model to review.

Guys, I will see you again next week.

James Reeves

• NRA-licensed concealed weapons instructor, 2012-present
Maxim Magazine’s MAXIMum Warrior, 2011
• “Co-Director” [air quotes] of TFBTV
• Former Regional Sales Rep, Interstate Arms Corp., MA
• Champion, Key West Cinco De Mayo Taco Eating Competition
• GLOCK® Certified Pistol Operator, 2017-2022
• Lawyer
► Instagram: jjreevesii
► Twitter: @jjreeves
► Vimeo: JJReeves
► 500px: JJReeves


  • Bob

    Why are the firearms community all of a sudden waking up and recognizing the 458 SOCOM? Tired of the AR15? This chambering for the AR15 platform has been around for quite a while. I played with it a couple of years ago, and found it has such limited uses, it just didn’t hold my interest. Plus, it was wicked expensive to shoot. If you have a need for a fast firing rifle that gives 45-70 ballistics, it’s the best option. Only you can decide. If you use an AR for hunting, the 223, 6.5 Grendel, and the 6.8 SPC, are more than adequate for medium range varmints, hogs, deer, and antelope. I have taken all with good results.

    • JumpIf NotZero

      [556] has such limited uses

      lol. Ok, go shoot 458 past 100y and talk to me about limited uses.

      • Bob


      • Bob

        I don’t think you grasped the point of my post. I’m not disparaging the 458 SOCOM, I’m just wondering why after all these years the firearms community is talking about it so much. It’s a great short range stopping rifle in the AR platform, which I think is the best, over the 50 Beowulf, due to the greater availability of bullet choices. My favorite 458 SOCOM load was the Barnes 300 over H110 @ 1850 fps. An awesome HOG load. I sighted my scope at 100 yard zero. Anything inside that was “dead meat”.
        So, you 458 SOCOM, 50 Beowulf Fan Boys,…. Chill! have fun with your rifles. I’m with you!

        • LG

          Hornady could be used as a reason for lack of press and fanfare with the 458 SOCOM. Hornady’s brainchild, the 450 Bushmaster, pales in comparison to the 458 SOCOM.

          • Bob

            Can’t we all just get along? 🙂 Guys, let’s stop arguing, and agree. The AR Platform is the greatest firearm designed in the last 1/2 century!?

        • DrewN

          I’ve had a ‘wulf almost since it launched and I wholeheartedly agree .458 is the better chambering,esp. with the AR-10 boltface.

      • iksnilol

        Uh, reading comprehension wasn’t taught at Delta?

        He obviously said that .458 SOCOM has limited uses so it didn’t hold his interest.

  • Richard

    Why the .458 SOCOM? Well why not?

  • Rob

    The 458 SOCOM was designed to fit in an AR-15, and now it has been put into a hybrid AR-10 with an AR-15 magwell. I actually like the idea since the biggest knock with a lot of the AR-15 alternate calibers is the weakening of the bolt. It’s just a little funny. Just once could be we design a great round FIRST, and THEN design a rifle around it? It this platform they probably wouldn’t need to mess with a rebated rim if the round hadn’t already had one because it was meant for the smaller AR-15 bolt.

    BTW, a semiauto 45-70? What’s not to like? 😉

  • Bill

    I didn’t realize it was for hunting. I thought it was either for the first guy in the stack or use as an anti-materiel gun.

    • Anonymoose

      First guy carries a shield and an SMG or handgun, and this doesn’t have the range for an anti-materiel gun. The .458 was envisioned as a thumper for big game and theoretically CQB.

  • Joe

    Perhaps he should shoot some real rifle rounds instead of rounds good for woodchucks and Prairie dogs. I can’t imagine it kicks any more than a 308.

    • gordon

      Just run the numbers through a recoil calculator. It often does kick more. Momentum being a bigger factor than energy in recoil. Momentum is conserved.

    • Anonymoose

      You should look at the .45 Raptor. It’s basically a .460 S&W with the rim trimmed for use in a .308 rifle. It outperforms .458 SOCOM and gets full capacity out of (modified) .308 Pmags.

  • gordon

    I was unaware that the current .458 SOCOM AR-15s are failing. Are they? If not, why pay more and have a less standardized weapon?

  • Kevin Harron

    “So you’re basically cutting your capacity by a third.”, uh, no, you are cutting it by 2/3…

  • Big Daddy

    It has a use and this seems like a good rifle. I like my Mutant, it’s overbuilt for the round actually. I think If I were in black bear and Hogzilla country this would be a good choice with my G20. Since I’m not I don’t really need this, I don’t need the G20 either, the Hogs here in Texas don’t grow to that size and there’s no bears in Central Texas. If indeed this does match the 45-70 I think I’d rather carry this over a lever action 45-70. If I were in Brown Bear country, being able to get off twice as many shots before it’s on me sounds like a great idea. Add a laser/light and pop,pop, pop, pop, pop and maybe you’re not bear food.

    The idea of not having as many rounds in the mag misses the point. The whole idea is to not need a lot of rounds. It’s hunting not war. One well placed shot and done is the idea. No need for a 30 round mag.

    I always though this round would make a great short range rifle at security check points. Supposedly it was one of the design ideas for it, take the engine out. I think it also had some Maritime uses also. If I was outfitting a security force I would consider this rifle for taking out vehicles quickly, more accurate and effective than a 12 gauge with slugs. When it came out they used the 90 round drum, I think it took 33 rounds of .458.