Range Review: CMMG Banshee 10mm

posted on November 20, 2019

One of the hottest introductions to the Pistol Caliber Carbine (PCC) arena in recent years, CMMG’s Banshee has given shooters a compact, highly accurate AR pistol or SBR platform available in everything from 9mm to .300 BLK. What’s been lacking, at least in the mind of many shooters is the highly anticipated 10mm variant.

That all changed with the recent introduction of the Banshee 300 Series Mk10 10mm, which is available both in AR-pistol and SBR configurations. Featuring an 8-inch barrel and six-position adjustable proprietary RipBrace on the AR pistol, the 10mm Banshee boasts an extremely nimble overall length of 24.3 inches, allowing it to be handled easily in tight confines, as well as transported in a compact package. Likewise, the 10mm delivers enough punch to make it ideally suited for personal-defense or hunting purposes.

One of the main reasons for the absence of a 10mm AR pistol until now was the wide variety of factory 10mm ammunition on the market and the extreme range of loadings, from rather hot to basically anemic. Because ammo velocities and pressures vary so much, it’s hard to design a gas-operated AR pistol that can successfully handle nearly everything on that broad spectrum.

The brilliant solution from the folks at CMMG is the Radial Delayed Blowback operating system, which uses a mechanically induced delay in the cycling of the bolt, thus allowing pressure to escape through the barrel prior to the cycling of the bolt. This helps stabilize the short gas-operated system across loadings and reduces recoil for higher pressure loadings.

Likewise, CMMG includes three different buffers with the shipment of the Banshee 10mm with instructions for each. Depending on a given load’s power factor (bullet weight x muzzle velocity / 1,000) or use of suppressor, a different buffer should be installed. The pistol comes with the pre-installed H3 buffer, which handles a power factor greater than 190 but less than 230; a carbine buffer is included in the box for power factors less than 190; and a CMMG 8-ounce buffer is included for suppression or a power factor over 230. While the H3 buffer may successfully operate with various loads, the other two buffers allow for fine tuning and optimal long-term reliability of the Mk10.

The other unique feature on the Banshee 10mm is a bolt that locks back on an empty magazine, something lacking on many PCCs. The engineers at CMMG call it the Bolt Catch Linkage System, which allows for faster, more conventional reloading. Throughout testing, the bolt locked back reliably without any failures. Likewise, the magazine drops free with the press of the right-handed magazine release button, making reloading as seamless a process as possible. 

Speaking of magazines, the Banshee 10mm shipped with two 30-round SGM magazines, both of which are built in the Glock style. CMMG claims the spring in the SGM is stiffer than a Glock mag, making it more suitable for long-term usage in the AR pistol configuration, but at least in short-term testing, the Banshee runs Glock mags without a hitch. 

The remainder of the controls on the Banshee are ambidextrous, including the CMMG charging handle and safety selector. M-Lok attachment points allow for accessorizing at the 3-, 6-, and 9-o’clock positions along the CMMG RML7 handguard, while a continuous Picatinny top rail allows for a wide variety of optics (iron sights not included). The six-position CMMG RipBrace is the difference between an AR pistol and SBR, as well as a mountain of fees and NFA-related paperwork. The 1:16-inch twist and 8-inch barrel seemed to handle a wide variety of 10mm ammunition, from Hornady’s 155-grain XTP to Federal Premium’s 180-grain Hydra-Shok JHP. For testing, the standard H3 buffer was used without any issues.

At just 24.3 inches in overall length (collapsed), the Banshee 10mm is extremely nimble, making it easy to operate on steel targets and easily stored and transported when not in use. While stout in a 1911-style handgun, the 10mm produces little recoil in the AR pistol, allowing for all-day comfort when burning through brass. The SV Brake helps keep muzzle rise and recoil to a minimum, too, and can be removed to add a suppressor.

The Banshee, which was paired with a See-All open sight, was tested at 25 yards from a standing bench and sandbag rest. The best group of the day came with Hornady’s Critical Duty 175-grain FlexLock, which measured .87 inches on five consecutive shots. Another industry-leading defense load, Federal’s 180-grain Hydra-Shok produced a best group of 1.12 inches, with an average of 1.18 inches.

Lightweight, highly maneuverable and specializing in concealment in a pack or truck, the Banshee 10mm packs a hefty punch. Whether you’re looking for a hard-hitting truck gun or to drop the hammer on a sounder of rogue hogs, the highly accurate and ultra-reliable Banshee 10mm is up to the task.

CMMG Banshee 300 Series Mk10 10mm Specifications

Manufacturer: CMMG; (660) 248-2293, cmmginc.com
Action Type: Semi-automatic, Radial Delayed Blowback
Caliber: 10mm
Capacity: 30
Receiver: Forged 7075-T6 AL Lower, Upper
Barrel Length: 8 inches
Barrel Twist: 1:16-inch 
Barrel Contour: Medium Taper
Accessories: Two SGM 30-round Glock magazines
Pistol Brace: CMMG RipBrace, six position
Pistol Grip: Magpul MOE
Sights: None; Picatinny rail for optics
Trigger: CMMG single-stage Mil-Spec
Weight: 5 pounds, 9 ounces
Length: 24.3 inches


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