CMMG Banshee MK17 Review : 300 Series (Premium PCC Option)

by Travis Pike

January 6, 2021



The world of PCCs/Subguns has gotten a little bigger with the advent of the ultra-modern and feature-filled CMMG Banshee Mk17. This super-compact AR pistol uses P320 magazines and draws its name from the M17 handgun in use by the US Army. CMMG was kind enough to shoot me one over for a Gun University CMMG Banshee Mk17 review.

CMMG Banshee MK17 300 Series Specs

  • Capacity 21
  • Caliber 9mm
  • Overall Length 18.9″
  • Barrel Length 5″
  • Weight 4 lbs 10 oz
  • MSRP $1,549.95

CMMG Banshee MK17 300 Series Background

The CMMG Banshee series is hard to pin down. They come in calibers ranging from 9mm to 7.62×39 and use a wide variety of magazine platforms.

One thing they all have in common is that they are superbly small. They feature short barrels and come in both SBR and pistol variants.

The compact and lightweight design makes them a perfect candidate for home defense purposes, especially this model.

It features a 5-inch barrel and weighs a mere 4 pounds 10 ounces.

This teeny-tiny gun is perfect for inside the home and would be an excellent tool for those who may not be able to handle a full-sized rifle, or shotgun, and knows how hard a handgun can be to shoot accurately.

The Banshee Mk17 is also easy to suppress, and with a suppressor present, the length is still shorter than a standard AR 15 with a 16-inch barrel.

And it’s also an excellent weapon for those who already own the P320 family of handguns. The ability to share magazines could be a valuable commodity or just plain convenience.

The Mk17 is also an alternative to most standard blowback operated AR 15 PCCs. The Banshee is blowback operated but uses a rotary delayed action that reduces some of the issues blowback PCCs run into.

If you’re looking for a premium option for a PCC, then this one makes its way into the arena as a top contender. In fact, it made it on our list of Best Pistol Caliber Carbines. Premium also means a rather high price admittedly, and the value is going to be subjective in a lot of ways. The Mk17 comes in three different series. The 100, 200, and 300. This is the 300 series and is the most feature-filled and most expensive option, so if you wanna ball, this is the baller choice.

CMMG Banshee MK17 300 Series Features

1 Ambidextrous Safety

Ensures that your gun is always safe and at the ready.

2 Ambidextrous Charging Handle

Allows for easy operation for either righties or lefties.

3 Cerakoted M-LOK Handguard

Well-designed handguard allows for the attachment of small accessories.

4 1/2″ x 28 Threaded Barrel

Allows for the use of a suppressor.

5 CMMG Ripbrace

Nice brace that adds lots of stability and comfort.

CMMG Banshee MK17 Variants

The Banshee MK17 actually comes in three different series: the 100, 200, and 300. And as the number gets higher, so does the amount of cool features and options. And just so you know… the 300 series comes in 10 different Cerakote options.

CMMG Banshee MK17 – Our Take

Shooting PCCs is a lot of fun and something I always enjoy. The Banshee Mk17 is no different. I’ve enjoyed shooting it quite a bit and have been using mostly 124 Grain Winchester white box, but also tossed in a fair share of SIG Sauer’s M17 JHPs. It just seemed appropriate to use M17 ammo in the Mk17.

I just hit 510 rounds as I type this. That includes 450 rounds of FMJs and 60 JHPs. The gun eats it all and does so with indifference. I applied a little lube a few days ago, and that was all the maintenance applied to the weapon. Unless you count sweat as lube because its Florida and sweltering outside.

How it Handles

The safety and charging handle are both ambidextrous and quite easy to engage with. The charging handle in particular is massive, and this makes the gun easy to rack. The magazine release is unusual but smartly designed to accommodate a pistol magazine in a AR 15 platform. You can easily reach it with your trigger finger, and it’s light, so it requires very little pressure to accentuate.

The Ripbrace is an excellent addition and is a modified SBA3 brace that allows for instant deployment to one of five positions. It slides rearward with little effort and locks into your chosen position via a simple set screw. The brace provides a lot of stability and comfort to this AR pistol.

The handguard is very short and provides just enough room to allow you to grip it. Because it’s so short I prefer to use a magazine well grip. It’s a bit more comfortable. The gun is so short and light that there are no major control concerns with such a grip.

Does It Shoot Straight?

One of the things I was most impressed with was the gun’s accuracy. 9mm is still a pistol round and is not a round designed for exceptional accuracy. I’ve never seen a PCC be a 1 MOA gun. The Banshee Mk17 was capable of shooting a 2-inch group at 50 yards with a red dot and hasty prone position. Inside of 25 yards, you can make sub-1-inch groups all day long.

It’s an impressively accurate PCC. The trigger is a simple Mil-Spec model, but that doesn’t mean it’s bad. Not all ‘Mil-Spec’ triggers are equal, and I find this one to be quite clean and crisp. The trigger reset is a real chunk and is impossible to miss.

…But how does it feel?

The best part of the rotary delayed system is that the recoil you typically feel from blowback PCCs is wholly gone. Many straight blowback PCCs have about the same recoil as a 5.56 rifle. The Banshee Mk17 has superbly light recoil, akin to something like the MPX with its light-recoiling gas system.

The 5-inch barrel is perfect for a 9mm round, and even as I shot into the early evening, there was no real muzzle flash. Or at least not any that is perceivable to the shooter. This lack of flash includes the self-defense JHPs I tested. A low flash reaffirms my thoughts on the gun being an excellent home defense weapon.

What about the Value?

Oof! This is not a cheap gun, the series 300 Banshee Mk17 costs $1,549.95 according to the gun’s MSRP. The 100 series with it’s simpler loadout is about 350 bucks cheaper. The 300 series and it’s enhanced controls, brace inclusion, and cerakote finish are certainly worth the cost.

It’s a premium grade firearm, and I don’t necessarily think it’s overpriced. What I don’t like is the fact it only comes with a single 21 round SIG magazine. An extra magazine or two would be a welcome inclusion at this price point.

CMMG Banshee MK17 300 Series PROS AND CONS

  • Low Recoil
  • Lightweight, Compact Design
  • Accurate
  • Fun to Shoot
  • Price
  • Expensive Magazines

Report Card


No issues whatsoever with standard ball or JHPs. The gun functions flawlessly with little maintenance required.


As far as PCCs go, this is top tier accuracy. 9mm isn’t a long-range round, so it doesn’t compete with dedicated 5.56 rifles, but it’s a real banger for the platform. 


The rotary delayed action reduces recoil significantly and makes it a very soft and comfortable shooter. The recoil and muzzle rise is nothing, and the gun is a joy to shoot. It’s a gun that I want to shoot more and more of. 


Lots of ambidextrous controls, the Ripbrace, and well thought out magazine release make this ergonomically very sound. The light and compact design make the gun very handy. 


This is one expensive PCC, and the 1,500 and change MSRP is a tough one to sell for most people. The gun is feature-filled and not necessarily overpriced, and it’s a premium grade gun with a premium grade price. I do think at this price point you should get more than one magazine, especially when the SIG magazines are so expensive. 


Our Grade


Reviewed by Travis Pike

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Based on 3 Reviews

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CMMG Banshee MK17 Starter Pack

If you going to invest in CMMG’s latest offering, it only makes sense that you have the bare minimum to properly own and operate this weapon.

Keep in mind, the CMMG Banshee isn’t the cheapest option out there. But performance-wise, it’s hard to beat. Investing in these basics not only ensures that top-notch quality you’re expecting but your safety as well.

CMMG Banshee MK17 Gun Deals

With the higher price of the Banshee, it’s imperative to find a great deal. However, it’s getting harder and harder to find quality munitions these days. As of now, the only available seller for the MK17 is the manufacturer.

But we’ll keep tabs and update this list as more sellers become available.

Disclaimer: These are priced at time of writing. Prices and availability are subject to change.

Upgrades and Accessories for the CMMG Banshee MK17

Once you get your hands on one, you’ll probably want to invest some more into it to really make it your own. These upgrades are what we recommend to get you started.

Best Accessories for the CMMG Banshee MK17

AccessoryDetailsCheck Price
Viking Tactical Quick Adjust Sling
  • 2 point design
  • Padded for Max Comfort
  • Quick Pull Tab for Rapid Adjustments
Check Price
Surefire X300U-A
  • 1000 Lumens
  • Large Center Spot Beam
  • Easy to Mount
  • Ambidextrous Switching
Check Price
Sig Romeo 4H Red Dot
  • Cowitness QR Mount and Low Mount Included
  • IPX-7 Rated
  • Over 50,000 Hour Battery Life
Check Price
Sig SRD 9 Silencer
Sig SRD 9
  • Stainless Steel Baffles for Durability
  • Lightweight and Maneuverable
  • Shoots Great with Subsonic Rounds
Check Price

Best Ammo for Your CMMG Banshee MK17

Honestly, the CMMG Banshee is just too much fun to shoot. But if you’re not careful, your PCC won’t just eat up ammunition but your wallet as well. That’s why you should pickup some 9mm ammo designated strictly for the range and some to use as working rounds.

Range Rounds


MagTech 9mm 115 GR FMJ Ammo

Cost Per Round
Natchez Shooter’s Supply $0.24
Brownells $0.23
Palmetto State Armory $0.34

Working Ammunition


Barnes 9mm 115 GR Ammo

Cost Per Round
Palmetto State Armory $0.92
Natchez Shooter’s Supply $1.15

CMMG Banshee vs H&K MP5k

A common comparison is the CMMG Banshee vs the H&K MP5k. To help show how it contrasts and how some of the above information I presented comes into play when looking at a more expensive version, you might get a bit more of an understanding of my pros and cons.

Information on the Banshee MK17 is limited. However, we’ve compiled a list of resources to help you better understand this weapon.


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About Travis Pike

Travis is a former United States Marine Corps Infantryman and currently a firearms writer, instructor, and works in Emergency Management.

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