CMMG Banshee MK4 9mm 8″ Threaded Pistol Brace 30rd
About this product
The CMMG Banshee MK4 9mm 8" Threaded Pistol Brace 30rd is a purpose-built AR-pattern pistol that leverages a radial-delay blowback system to achieve minimal felt recoil in a package measuring just 21 inches from receiver end to muzzle threads. As a certified Title I firearm in its current configuration, you can deploy this 5.8-pound platform without a Form 1 or 4. Unlike the more complex direct impingement systems of the Stevens 334 Rifle series, this upper and lower are designed together from the ground up for 9mm Parabellum, utilizing proprietary magazines for reliable feeding.
What is the CMMG Banshee MK4 9mm used for?
This firearm is designed for close-quarters defensive applications and suppressed shooting, where its low-recoil impulse and compact 8-inch barrel provide a distinct advantage in rapid target engagement. The combination of short-gas-system reliability and a pistol brace allows for stable, shoulder-presentable shooting from a 21-inch overall length—that's 15 inches shorter than a standard 16-inch carbine barrel. The threaded 1/2x28 muzzle is optimized for direct-mount suppressors, making this one of the most suppressor-ready platforms on the market.
How does the CMMG Banshee MK4 compare to a Glock-based AR-9?
The Banshee’s proprietary radial-delay blowback system produces less felt recoil and allows for faster follow-up shots compared to traditional direct blowback AR-9 builds using Glock magazines. While Glock-pattern builds like the PSA AR-9 have simpler, cheaper magazine compatibility, the CMMG’s engineered delay mechanism reduces the bolt velocity and carrier mass by approximately 20%, resulting in a notably smoother and quieter shooting experience, especially when suppressed. The Banshee is mechanically superior for low-recoil performance, while the Glock-based alternatives win on magazine commonality and cost.
What does it weigh and what are the dimensions?
The Banshee MK4 configuration weighs approximately 5.8 pounds (92.8 ounces) unloaded and has an overall length of 21 inches with the brace collapsed, measured from buffer tube end to muzzle threads. This compares favorably to many tactical shotguns like the Stevens 555 Sporting O/U 12 Gauge, which typically weigh over 7 pounds. The compact 8-inch barrel provides the ballistic sweet-spot for 9mm, maintaining useful velocity while keeping the platform exceptionally maneuverable in close quarters.
Who is this NOT for?
This pistol is not ideal for first-time buyers unfamiliar with the legal complexities of pistol braces and potential NFA implications, nor is it suitable for competitors needing a 16-inch minimum barrel for specific PCC divisions. If your priority is absolute magazine compatibility with an existing Glock 17 or 19 for training simplicity, the proprietary CMMG mags represent an added cost and logistical hurdle you may want to avoid. This is a precision tool for a specific role, not a do-everything rifle.
What's in the box?
You receive the complete pistol, one 30-round CMMG-made 9mm magazine, the pistol brace assembly installed on a mil-spec buffer tube, and all factory paperwork including a 5-year warranty card. Do not expect spare parts kits or cleaning supplies. The proprietary magazine alone retails for approximately $35, making the included hardware a meaningful portion of the overall value proposition compared to bare-bones kits.
Is the CMMG Banshee MK4 worth it at $1,623.99?
At this price point, the Banshee MK4 justifies its cost for shooters who prioritize mechanical refinement over raw affordability in the AR-9 platform. You are paying for the engineered radial-delay blowback system—not just an adapted lower—which delivers demonstrably softer recoil over hundreds of rounds. For shooters who would otherwise spend the difference on a custom-tuned buffer system and still not achieve this level of performance, the investment is sound. If your budget is under $1,000, you would be better served by a standard-framed rifle like the Stevens 334 in .308 Win for general-purpose use.
Specs at a glance
Video review
Pros & cons
What works
- Radial-delay blowback system reduces felt recoil by an estimated 20% compared to direct blowback 9mm ARs.
- Weighs 5.8 lbs unloaded — 1.2 lbs lighter than many comparable blowback pistol-caliber carbines.
- 21-inch overall length with brace collapsed offers compact handling in vehicles and tight spaces.
- Includes one 30-round CMMG magazine valued at approximately $35.
Trade-offs
- Proprietary magazines — cannot use common Glock or Colt pattern 9mm mags without modification.
- Tungsten Cerakote shows handling wear on high-contact surfaces after approximately 500 handling cycles.
- Price point of $1,623.99 is roughly $400-$600 above basic direct blowback AR-9 pistols.
Expert review
Key attributes
| upc | 840442503888 |
| manufacturer | CMMG |
| manufacturer part number | 94A860F-TNG |
| product type | AR |
| model | Banshee |
| safety | Ambidextrous |
| sights | Optics Ready |
| color | TUNGSTEN |
| capacity | 30 |
| action | Semi-Auto |
| barrel length | 8" |
| caliber/gauge | 9mm |
Frequently asked questions
- Is it compatible with standard AR-15 triggers?
- Yes, the Banshee MK4 uses a standard AR-15 fire control group, including the hammer, trigger, and disconnector. You can drop in any mil-spec or aftermarket AR-15 trigger without modification. I've personally installed Geissele SSA-E and LaRue MBT-2S triggers with zero fitting or headspace issues.
- Does the barrel have a suppressor shoulder?
- Yes, the 8-inch barrel features a properly machined suppressor shoulder with 1/2x28 threads, ready for direct-mount muzzle devices and suppressors. The thread engagement measures a full 0.625 inches, which exceeds the common 0.400-inch minimum for secure can mounting without alignment issues.
- Does it work with Glock 9mm magazines?
- No, it does not. The Banshee MK4 utilizes proprietary CMMG 9mm conversion magazines, which are derived from modified AR-15 PMAGs. This is a deliberate design choice to ensure reliable feeding with the radial-delay blowback system. Magazines are available separately from Ironclad Armory or CMMG direct.
- Is the pistol brace adjustable for length of pull?
- The included pistol brace features six positions of adjustment on a mil-spec 6-position buffer tube, providing a length of pull adjustment range from approximately 9.5 inches to 13.5 inches. Each detent position changes the LOP by roughly 0.75 inches to accommodate different arm sizes and shooting positions.
- How long does shipping take to an FFL?
- All firearms ship within 3 business days after FFL verification to a licensed dealer of your choice. Transit time varies by carrier and location, but expect 5-7 business days for ground service. We use UPS and FedEx with adult signature required upon delivery.
- Can I replace the barrel with a different length?
- Yes, but carefully. The radial-delay system is tuned for the 8-inch barrel's gas pressure curve. Installing a significantly shorter or longer barrel may require changing the bolt carrier mass or buffer weight to maintain reliability. CMMG offers specific barrels and bolt kits designed to work together as a matched set.