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Banshee Mk17 Review – It Doesn’t Take Glock Mags

CMMG marches to the beat of their own drum making a better gun industry along the way. In a world where the AR-15 appears to move forward in millimeters, CMMG keeps the industry's attention. Their half-Kalashnikov, half-Stoner “Mutant” lead the charge for something off the beaten path, followed by the warhammer-like Anvil in 458 Socom. Now, we have the Banshee series of pistols and SBRs released in various calibers and magazine configurations. We took the opportunity to try out the MK17 variant of the Banshee. 

The Mk17 utilizes the Glock-conquering P320 magazines. The P320 conquers the competition over and over and has staying power. CMMG has several Banshees that allow the user to share magazines between their primary subgun and their pistol, and the Mk17 takes that role with the P320 series. 


The various Banshee models have little in common. More than merely another AR-15 style 9mm carbine, some variants range in calibers from 22 LR to 7.62×39. The small and loud nature of these pistols ties them together. Yet centerfire pistol-caliber Banshees present their own fascinating operating system to shake up the pistol caliber carbine scene. 

You can predict how a company will make a PCC these days with almost boring regularity. Most often starting from the trusted AR platform, transition it to use Glock magazines, and toss in the old blowback operation design. CMMG bucked that trend and ditched the traditional blowback design for their patented radial delayed blowback. 

The radial delayed blowback makes use of a proprietary bolt carrier group and bolt. You might not notice much difference between a radial delayed bolt and a standard AR 15 bolt. The bolt lugs have angular cuts for unlocking from the chamber. 

The bolt rotates and locks into the chamber as the bolt goes forward. After a round discharges, the bolt rotates and unlocks before flying rearward and completing the operations cycle. The delay allows pressure to decrease before it unlocks. 


A traditional blowback system requires something heavy. The heavy portion varies between a heavy bolt like the Scorpion, a heavy spring like the SUB 2000, or a combination of a heavy buffer and spring that lives at the heart of most blowback ARs. The Banshee Mk17 does away with the need for a heavy anything. Racking the Banshee’s charging handle gives little resistance and its glide rearward stands out among its AR-style 9mm cousins.

The Banshee Mk17 also does away with the heavy recoil associated with blowback PCCs. Most blowback PCCs chambered in 9mm have the recoil of a 5.56 AR 15. While light, the fact that a 9mm hits back like a real rifle cartridge displays a certain inefficiency in the blowback design. The Banshee eliminates recoil inefficiency and gives proper pistol caliber recoil. 


Okay, the Mk17 lacks leather, but Ricardo Montabaum could still narrate this review. The Banshee occupies a top slot when it comes to desirable features. The Banshee Mk17 comes in three different tiers labelled 100, 200, and 300 series. Each built around the same operating system and receiver, the differences come down to furniture The most basic 100 comes without anything on the buffer tube, where the 200 series gains a Ripbrace and other smaller features. This review focuses on the 300 series, which occupies the premium grade spot both quality and price, even down to the Cerakote.  The 300 series wears the CMMG Ripbrace, features an ambidextrous safety and charging handle, 10 different cerakote finish options, Magpul grip, and a threaded suppressor ready barrel. 

The 100 and 200 series vary in features and have a lower price point. The 100 series lacks a brace, and utilizes an A2 grip and flash hider. The 200 series has a CMMG muzzle brake, Magpul pistol grip, and a CMMG Ripbrace. The 100 series uses right-handed safety and the 200 series has an ambidextrous safety. The 100 and 200 series wear mil-spec charging handles. A simple black anodized finish adorns both the 100 and 200 series. 

Should the price of the lowest-cost model still not appeal to you, CMMG does sell the proprietary barrels and BCGs separately for a DIY build. 


Right out of the gate the first bang makes the reduction in recoil noticeable for experienced PCC shooters. Shooters get more pew and less bang on both ends when compared to subguns like the CZ Scorpion. The Banshee Mk17's radial delayed action proves its merit when it barely moves when fired, combining low recoil and minimal muzzle rise for a controllable package.

Control like this makes it quite tempting to dump a mag for the fun of it. The Banshee’s radial delayed system effectively reduces blowback recoil as well by a notable degree. When ran side by side with the CZ Scorpion the Banshee feels noticeably less jarring. The Scorpion weighs two pounds more than the Banshee, yet the massive bolt forces the gun rearward and muzzle upwards to a much greater degree than the Banshee allowing you to drive the latter with greater efficiency.

The 5-inch barrel of the Banshee Mk17 does limit its range. Between 5 to 50 yards, it dominates without complaint printing sub-two-inch groups at 50 yards. Beyond that, the gun shows some weakness. At 100 yards, the Banshee can hit a target but won’t split a playing card. During our testing, the Banshee produced four to six-inch groups at 100 yards but rings a ten-inch steel gong at 100 yards with nothing more than the Meprolight Foresight and a stable standing position. 

The 9mm chambering makes running the gun with a match type trigger difficult as the more violent action of blowback systems have a habit of breaking match-type AR 15 hammers. PCC trigger options exist, but CMMG ships the Banshee with their own mil-spec trigger. Like most things mil-spec, a spectrum of quality exists between designs and manufacturers. The CMMG trigger runs tight and light with a powerful and noticeable reset. 

CMMG banshee mk17 trigger


From a practical standpoint, the Banshee Mk17 works as a defensive weapon. The short-range accuracy and control factor outline the carbine as suitable for aggressive close quarters training. After running through several combative shooting drills like the VTAC 1 to 5 drill, the box drill, and even a classic El Presidente drill, the Banshee showed potential as an effective fighting weapon. It checked the boxes for reliability and accuracy while treating the shooter to a lighter recoil impulse than many 9mm carbines. 

The Banshee can make accurate and effective hits on target against the clock with ease. The low recoiling design makes delivering round after round on target with great speed and accuracy far from difficult. The Mk17 has minimal perceivable muzzle rise when measured with a red dot. The dot jumps just a bit as the gun coughs and shot recovering takes fractions of a second. The easy handling nature of the gun can stroke your ego.

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The Banshee Mk17 eats well and digests whatever you need it to. From cheap target ammo to SIG’s M17 JHPs. The Banshee isn’t maintenance picky either. It runs filthy dirty without a drop of lubricant or the touch of a brush. 


Scoring high in the ergonomics department, the Banshee Mk17 sports a massive, ambidextrous charging handle, ambidextrous safety, and magazine release. CMMG address perceived AR 15 weaknesses and enhanced the weapon for lefties and switching shoulders. 

The massive charging handle stands out and offers you the ability to blade the charging handle into action. This crude method requires no gross motor skills and embraces the caveman part of your brain.

cmmg banshee mk17 charging handle

The Banshee Mk17 weighs a mere 4 pounds and 10 ounces and has a total length of 18.9 inches with the brace collapsed. Compact describes the Banshee perfectly. The Ripbrace deploys instantly with a tug of the modified SBA3 brace. The Ripbrace allows you to pick one of five positions for instant brace deployment. The brace will stop at whichever predetermined place you set. 

The ultra-short handguard sports a built-in hand stop to protect your hand from slipping in front of the short barrel. The short rail offers enough room to mount a light, and the OWL fits perfectly.


The lightweight and compact Banshee Mk17 packs a potent punch. The Mk17 would make an excellent home defense weapon for someone who lacks the strength for a proper rifle or shotgun. The Mk17's design makes it easier to shoot than any handgun but light enough for one-handed use. 

The 9mm round costs very little compared to rifle rounds in a normal market. Affordable ammo translates into more accessible training and without proper training, you can't call yourself armed. The Mk17’s reliable design ensures shooters have a capable home defense weapon as well as a range toy. The threaded barrel begs for a can, and even with a suppressor it would't take up more space than a traditional rifle. 

On the opposite side of the coin, the Banshee Mk17 makes shooting fun for all ages. While the AK 47 can be found in the hands of child soldiers around the world, better options exist for younger shooters. Something light, compact, and low recoiling makes a much better choice. The Banshee ticks all those boxes. 


From function to design, the Banshee Mk17 has it all. CMMG has built a gun that’s accurate and reliable. The Banshee Mk17 only comes with a single P320 21 round magazine. With a price point north of $1,500, a second magazine isn't much to ask. 

Also, the MK17 lacks compatibility with Elite Tactical System’s polymer magazines. These specific magazines do not lock into the gun and seem tight into the magwell. The low price makes these mags attractive, but their lack of function eliminates that attraction. Stick to traditional SIG P320 magazines and the Banshee Mk17 runs like a clock. 


The Banshee Mk17 joins a line of winning designs. The Banshee series challenges the norm with calibers like the 10mm, 5.7, and beyond. The Mk17 gives the P320 users a subgun option for those looking to match their magazines. Contrarians will appreciate the insurgency against Glock magazines and their PCC dominance. 

As far as AR pistols the Banshee has a winning design with an excellent radial delayed system. In a day and age where AR platform prevalence remains unmatched, CMMG continues to push the system forward. 

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2 responses to “Banshee Mk17 Review – It Doesn’t Take Glock Mags”

  1. Pops says:

    Well I would want one that took Glock mags. The 320 MecGar mags are excellent, but a bit more pricey and I haven’t seen a 30 round P320 mag.. yet. Glock 30 round mags are common. Sig still needs work out either bugs or quality control on their 320 series, I have seen some QC variances among mine. But that’s a different article. I do like these Banshee’s though.

  2. Matt says:

    I get the whole radial delayed blowback action for recoil reduction. However the thing I like about my plain Jane blowback 9mm AR pistol is the fact that the recoil closely approximates (or slightly exceeds) that of a 16 inch 5.56 chambered AR. If I can learn to run the blowback 9mm AR fast, I can run the 5.56 AR rifle fast. Also, yeah, Glock mags please. Now, the Banshee 10mm, that I really like!

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