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As ambushes go, I probably couldn’t have picked a better—or worse—spot. I was hunting hogs on the Cactus Creek Ranch in South Texas with CMMG’s new MkW Anvil rifle, chambered in .458 SOCOM, and a couple of attempted stalks hadn’t worked out. Conditions were less than ideal: Several days of torrential rain had turned some of the ranch roads into gumbo, and maneuvering by vehicle or foot was a challenge. The solution was to set up on one of the ranch’s deer feeders and wait in the drizzling rain for the hogs to come to me.

The author tagged this Texas hog using CMMG’s new Anvil rifle loaded with a .458 SOCOM round from Underwood Ammo using a 300-grain Lehigh Xtreme Penetrator bullet.

The author tagged this Texas hog using CMMG’s new Anvil rifle loaded with a .458 SOCOM round from Underwood Ammo using a 300-grain Lehigh Xtreme Penetrator bullet.

Guide Jake Wiatrek and I set up on the edge of a small clearing about 50 yards from a feeder, with thick cover behind us and a thin patch of brush in front. When the feeder went off as programmed, I wasn’t quite prepared for the response—two different groups of hogs emerged from the thick cover on the run and converged on the feeder. Before we knew it, we were surrounded by about 60 hogs, a few of them moving within 10 yards of us.

I sat, frozen, next to a bush, with the rifle on shooting sticks, waiting for an opportunity to shoot a big boy in the center of the pack near the feeder. Anxious minutes crept by as I waited, but my chosen target always had pigs in front or behind him. With hogs milling all around us, and thoughts of General Custer’s final indiscretion flitting through my mind, I couldn’t believe we hadn’t been detected yet. That changed when a nearby hog finally caught our scent and snorted at us.

Things were about to get interesting.


In theory, at least, I knew that the Anvil and its .458 SOCOM round, delivering roughly the power of a .45-70, is a legitimate big-pig thumper. Of course, as with any other rifle/ammo combination, success depends on shot placement and the terminal ballistics of the bullet used.

The Anvil superficially resembles the AR-15 and accepts AR-15 magazines. However, its design is actually based on the beefier AR-10 platform with a larger bolt and bolt carrier group, incorporating lessons learned from CMMG’s popular Mutant platform, which is chambered in 7.62X39 mm.

The Anvil is sold in three different versions. The T model is the basic and lowest-priced version, while the mid-level XBE model sent to me for testing comes with a Magpul six-position carbine stock and Magpul MOE grip. The XBE2 model adds an upgraded, two-stage Geissele trigger with an MSRP bump of a couple of hundred dollars.

Weighing just 7.5 pounds unloaded, the Anvil is equally at home in tactical or hunting roles.

Weighing just 7.5 pounds unloaded, the Anvil is equally at home in tactical or hunting roles.

All models come with a medium-tapered, 16.1-inch stainless steel barrel protected with a matte-black, salt bath nitride finish. Barrels have a 1:14 rate of twist, which will handle a wide range of bullets well, especially when shooting heavier bullets suppressed. At the muzzle, which is threaded 5/8-32, you’ll find a CMMG SV muzzle brake that helps to mitigate the relatively lightweight rifle’s recoil, which I didn’t find objectionable. You’ll notice the recoil, to be certain—most notably when shooting heavier bullets—but experienced shooters shouldn’t have a problem with it.

Even though the Anvil uses an AR-10-type body, it’s been shortened and somewhat streamlined to help keep unloaded weight to about 7.5 pounds, which is considerably lighter than many AR-10 platforms. That makes the Anvil a reasonable choice for an everyday hunting rifle, as long as you’re hunting at modest ranges. The receiver has a dust cover, but there is no forward assist.

Otherwise, controls are in the usual AR locations and configuration, and they worked as they should. That’s the good news.

The bad news was the rifle’s GI-style trigger. It had quite a bit of creep and broke at an average pull weight of 6 pounds, 4 ounces. As a buyer, that’s the first thing I would change. I simply can’t abide a poor trigger and, more often than not, I end up replacing triggers on most AR rifles. As noted, CMMG does offer a more expensive version of the rifle with a better trigger.

One of the rifle’s more notable features is a carbine-length gas system using the SLR Rifleworks Sentry 7 adjustable gas block. This nifty piece of hardware allows you to meter the flow of gas via click adjustments to fine-tune the rifle to handle everything from supersonic 140-grain bullets to loads pushing 600-grain bullets at subsonic speeds.

There’s plenty of space on the Anvil to mount optics and accessories with a full-length Picatinny rail and CMMG’s RKM15 KeyMod handguard, which has a total of 48 slots in rows of 16 located at the 3, 6 and 9 o’clock positions.
The rifle ships with a single Lancer L50AWM magazine—a hybrid design with hardened steel lips and a polymer body. While the magazine will hold 30 rounds of 5.56 NATO ammo, CMMG has modified it for optimal performance with 10 rounds of .458 SOCOM ammo.

It’s important to note that if you live in a state with magazine capacity restrictions, you might not be able to purchase the Anvil with the included magazine. Some 10-round 5.56 NATO magazines, which will hold four rounds of 458 SOCOM, might work with the Anvil, but you should test them to confirm proper function.


Range-testing the Anvil was limited to four different loads, because the major ammo makers don’t yet load .458 SOCOM. You have to load your own or obtain ammo from several boutique or specialty ammo makers. The rounds used in testing were each unique and quite interesting. They included a Southern Ballistics Research (SBR) round loaded with a 300-grain brass Lehigh Defense Controlled Fracturing HP bullet and an SBR load using 140-grain Polycase ARX bullets. I also tested a Black Butterfly load with a 300-grain Nosler Ballistic Tip bullet and an Underwood load using the solid brass, 300-grain Lehigh Xtreme Penetrator bullet.

The nose of the Xtreme Penetrator bullet somewhat resembles that of a fat Phillips-head screwdriver. The manufacturer describes it as having radial flutes that “force the hydraulic energy inward, and then, as the energy is restricted, it accelerates outward creating high pressure spikes, damaging surrounding tissue.” The result, according to Lehigh, is exceptional penetration coupled with a larger permanent wound cavity.

With claims such as that, I quickly decided to take the Anvil and the Xtreme Penetrator out for a hog hunt— assuming the round shot accurately out of the rifle—to see how it performed for myself. Velocities for the three 300-grain loads were quite close, but the Xtreme Penetrator turned in the fastest average speed of the heavy loads at 1,916 fps. (The lighter, 140-grain Polycase ARX bullet was clocked at 2,579 fps).

Initial accuracy testing produced rather pedestrian results, with the first two loads turning in groups averaging over 2 inches at 100 yards. Groups with the Polycase ARX bullet tightened to an 1½ inches. I then moved on to the Underwood Xtreme Penetrator: The first three-shot group produced with that bullet really got my attention. It measured just 0.54 inch, with two bullets through the same hole.

Bingo! This would be my hog-hunting round, and it’s the load the Anvil was stoked with on that rainy day in Texas while I was surrounded by hogs.


As things turned out, I never got a shot at the big boar I had my eye on. One pig wandering close to us caught our scent and bolted, sending the entire herd thundering off into the cover. Happily, they didn’t all run in our direction.

We decided to wait a bit to see if any of the hungrier hogs would return, and they slowly began filtering back. I’d had enough of the rain and mud for one day, so I picked out a 100-pound sow, flicked off the safety and fi red. I was a bit surprised when the pig failed to drop in its tracks. I supposed I had expected the Xtreme Penetrator to hit like Thor’s hammer, but the hog ran off and was swallowed up by the Texas brush.

It took awhile to find the downed pig; we followed an on-and-off blood trail that was obviously the result of a lung hit. Jake Wiatrek proved to be part bloodhound, and we soon found the pig 60 yards from where it had been hit. I began to suspect that the solid-brass bullet had just penciled through, doing little damage. But that wasn’t the case: Field-dressing revealed that both lungs had been completely devastated.

Some hogs are just tougher than others and don’t go down easily—but they most assuredly will go down with a .458 SOCOM bullet in its vitals.

The round might have originally been designed as a close-range man-stopper for special operations forces, but it makes a very effective big-game cartridge within range limitations. Loaded in the Anvil, it’s hard to image a more effective big-bore AR package for working up close and personal.



  • ACTION: Direct-impingement semiauto
  • BARREL: 16.1 inch, medium taper, 416 stainless
  • RATE OF TWIST: 1:14
  • BARREL FINISH: Salt bath nitride
  • MUZZLE BRAKE: CMMG SV brake, threaded 5/8-32
  • RECEIVERS: Midsized Mutant platform, 7075-T6 aluminum
  • STOCK: Magpul six-position M4 carbine stock
  • TRIGGER: Single stage, GI-style
  • PISTOL GRIP: Magpul MOE grip
  • WEIGHT: 7.5 pounds (unloaded)
  • LENGTH: 33.5 inches (collapsed)

MSRP: $1,949.95




(660) 248-2293


Performance Results
Lead Avg. Muzzle Velocity (FPS) Avg. 100-yd Group (inches) Best 100-yd Group (inches)
SBR Controlled Fracturing HP, 300 grain 1863 2.1 1.83
Black Butterfly 300-grain, Nosler Ballistic Tip 1875 2.39 2.28
Underwood 300-grain, Xtreme Penetrator 1916 1.21 0.54
SBR Polycase ARX, 140 grain 2579 1.46 1.18

Accuracy testing was done with three three-shot groups per load. Velocity testing is averaged over five shots per load. Velocities were measured with a Competitive Edge Dynamics M2 chronograph. All groups were fired in a 6 to 12 mph wind at 100 yards.


Editor’s note: A version of this article first appeared in the March 2017 print issue of Gun World Magazine.