It has been an absolute year of renaissance for 10mm, which has me smiling from ear to ear. While last year gained us a great many pistols, we still had not seen a wide selection in, uh, bigger pistols. The kind that looks like SBR’s, but has a pistol brace which we always use in ATF approved configuration while shooting. Anyway…. A lot of submachine gun sized options did not exist for the centimeter, which I think is an absolute shame. But we laid hands on one this week that should be on your radar.

Hornady Custom 10mm used in testing.

The CMMG Mk10, from the Banshee series, is everything you want in a “pistol”. I am relatively new to the CMMG offerings, but I have been very impressed so far. The Mk47 might be the gun that put them on the map, but the Pistol Caliber offerings are absolutely a close second. And while they offer a wide variety of barrel lengths and calibers in the PCC class, the Mk10 stands alone in my eyes.

AR familiar controls

Starting the party is all the goodness we expect from the 300 series as CMMG standard. It is an AR-style of pistol, with familiar controls. It features an upgraded mil-spec trigger, which while it isn’t an AR Gold, is a vast improvement over standard AR triggers. It has CMMG’s own oversized charging handle, which is fantastic. It has the buttonless RipBrace, which means the stock brace deploys like greased lightning. Which is a lot of excellent stuff, but as I said, expected from the 300’s at this point. So what makes the 10mm so far ahead of the pack?

Magazine release with a big stick SGM 30 round mag.

Well, then we get to some not so standard features. While still part of the Banshee package, it is what really both sets CMMG apart and enhances the 10mm experience. First, we have a patented bolt hold open linkage, so the Mk10 gets bolt lock like a real AR. And then we have the radial delayed blowback system.

Oversized charging handle

The bane of a blowback PCC, as any of you that have picked one up know, is the heavy for caliber recoil. Even the anemic 9mm AR’s, if straight blowback, recoil harder than a 5.56 equivalent sized gun. Which kind of defeats the purpose. We have seen very few companies step up to address this. H&K and Ruger have handled it, albeit in different ways. But mostly it goes unspoken. And if it would be noticeable in 9mm, it would be much worse in 10mm.

The lower receiver

CMMG, never one to follow, saw this problem and decided to overcome it in a unique way. The patented radial delayed blow back system. Basically, the AR looking bolt has radiuses cut into the locking lugs. Through the magic of engineering, this absorbs some of the blowback energy into unlocking the bolt, as well as slowing down the returning inertia. Not only is it in theory soft, but it is also cleaner shooting since more of the gasses go down the barrel and out.

Bolt; heart of the radial delayed blowback system.

I was initially skeptical of this design because it sounds like snake oil. But I did notice in my 9mm review, it works. And in 10mm? Holy smokes. It works even better. The Mk10 is the softest shooting 10mm I have ever seen, as you can see by the hammering of targets in the review video. Recoil is basically unnoticeable, even with full power 10.

Unique carrier key

And that puts us in entirely new territory. Given the option of a PCC or an AR pistol in say, 300 AAC, I would have always chosen the 300 AAC prior to this. With a real AR buffer system, it would be faster shot to shot. But against the Mk10? I think not. And one could very easily argue that 10mm, short barrel against short barrel, is the best option. It makes a bigger hole, it is close in velocity, and the finished ammunition is lighter. And cheaper. And interchangeable with my pistol. And has bullets designed to expand at this velocity threshold. And makes for a shorter action, and therefore overall gun length. As the High Priest of the Cult of 10mm, there is nothing not to like about this new Gospel.

Mk10 muzzle brake

And then we have the finishers from CMMG. At a time when many prefer a tiny 4 or 5-inch barrel on a PCC, the Mk10 comes with an 8 inch. I personally don’t like guns in this class to go any shorter than 8, or else you really risk getting a finger out in front of the barrel. It is a trade-off of modern shooting techniques and design. If I am going to bother using a “pistol” size AR instead of a pistol, I want to shoot it like an AR. One must be very careful with a super short barrel. 8 inches is enough for most of us to just grab it and start blasting, which matters to me.

Arguably the best 10mm on the market.

You wanted more? Good. How about an M-lok handguard, perfect for flashlights and lasers. Standard. A muzzle brake built for 10mm? Included, and further reducing the recoil. High capacity? It ships with a 30 round SGM magazine. I thought this also a bold move, rather than using a Glock factory magazine. But I experienced zero issues. The Mk10 ran without a hiccup.


And oh my, was range time a winner. Using Hornady Custom XTP, I ran the Mk10 hard. Not only is it incredibly soft shooting, but it just goes and goes and goes. Topped off with a Trijicon MRO, this gun is incredible. I have shot a lot of 10mm guns in my life, so I say this with some weight behind it. The Mk10 is the best 10mm on the market, hands down. At any price. And I can offer no higher praise than that.

MSRP $1649.00