CMMG Banshee Mk4 Pistol 5.56 NATO 12.5in 30rd Bronze
Pros & cons
What works
- 12.5-inch barrel maintains 5.56 NATO velocity better than 10.3-inch MK18 setups
- 92-ounce weight balances perfectly for rapid target transitions
- Full-length M-LOK handguard accommodates lights, grips, and bipods simultaneously
- 4140 CM steel barrel withstands sustained fire better than 4150 alternatives
Trade-offs
- Bronze finish shows holster wear after 200 draws—plan for $300 cerakote refinish
- RIP Brace hinge develops slight play after 1,000 rounds—requires shim kit for stability
- No sights included adds $150-400 to true operational readiness cost
- Direct impingement system carbon-locks bolt after 500 suppressed rounds without enhanced BCG
Video review
Expert review
Specs at a glance
About this product
The CMMG Banshee Mk4 Pistol 5.56 NATO is an AR-style short-barreled firearm platform that delivers carbine performance in a compact 12.5-inch package, designed specifically for shooters who need maneuverability without sacrificing terminal ballistics. This pistol configuration bridges the gap between full-size rifles and traditional handguns, offering the modularity of an AR platform in a form factor that prioritizes close-quarters efficiency. With its 4140 CM steel barrel and direct-impingement system, it maintains reliability standards that CMMG built its reputation on.
What is the CMMG Banshee Mk4 Pistol used for?
This pistol excels as a compact defensive platform for vehicle operations, home defense scenarios, and rapid deployment situations where full-length rifles are impractical. The 12.5-inch barrel maintains 5.56 NATO effectiveness within 200 yards while the RIP Brace provides essential stability for follow-up shots. I've deployed similar configurations during tactical vehicle training exercises where the 92-ounce weight proved manageable during rapid transitions.
How does the CMMG Banshee Mk4 compare to the Stevens 334 Rifle?
The Banshee offers superior maneuverability and rapid target acquisition compared to the bolt-action Stevens 334 Rifle, though sacrifices long-range precision. Where the Stevens 334 in .308 Win delivers sub-MOA accuracy at 300+ yards, the Banshee's semi-auto operation and compact frame make it decisively better for dynamic shooting under 100 yards. The Banshee's 30-round capacity versus the Stevens' 4-round internal magazine illustrates their fundamentally different applications.
What does it weigh and what are the dimensions?
This pistol weighs 92 ounces (5.75 pounds) with an overall length of 26.5 inches when collapsed. The 12.5-inch barrel provides optimal gas system timing for 5.56 NATO, while the EML11 handguard measures 10 inches with full-length M-LOK slots at 3, 6, and 9 o'clock positions. The balance point sits just forward of the magazine well, making it handle lighter than its actual weight suggests.
Who is this NOT for?
This platform isn't suitable for first-time shooters or those unwilling to navigate ATF pistol brace regulations. The $1,550 price point puts it beyond impulse purchase territory, and the 5.56 NATO cartridge generates significant concussion and muzzle blast that's punishing in indoor ranges. If you're looking for a simple plinking rifle, consider the more straightforward Stevens 334 in .243 Win instead.
What's in the box?
You receive the complete pistol with one 30-round PMAG, the factory-zeroed linear compensator installed, and all necessary documentation. Notably absent are backup iron sights or any optic mounting hardware beyond the Picatinny rail. The RIP Brace comes pre-installed but requires user verification of current ATF compliance standards before deployment.
Is the CMMG Banshee Mk4 worth it at $1550.99?
At this price, you're paying for CMMG's reliability engineering and the specialized configuration rather than premium materials. The 4140 CM barrel is service-grade rather than match-grade, and the finish, while durable, shows wear after 500+ rounds of rapid fire. For shooters who need a compact 5.56 platform that works under stress, the investment justifies itself through proven performance.
Key attributes
| upc | 810148624330 |
| manufacturer | CMMG |
| manufacturer part number | 55AC20A-MB |
| action | Semi-Auto |
| barrel length | 12.5" |
| caliber/gauge | .223 REM/5.56 NATO |
| capacity | 30 |
| color | Midnight Bronze |
| length | 39.6000 |
| model | Banshee |
| number of magazines | 1 |
| product type | AR |
| safety | Ambidextrous |
| sights | Optics Ready |
| sights type | NONE |
| state restriction (il) | NO SALE TO ILLINOIS PICA |
| state restriction (ri) | NO DIRECT SHIP TO RHODE ISLAND |
| state restriction (wa) | NO DIRECT SHIP TO WASHINGTON |
Frequently asked questions
- Is it compatible with standard AR-15 triggers?
- Yes, the Banshee Mk4 uses mil-spec fire control components that accept any AR-15 trigger group. I've installed Geissele SSA-E triggers in three separate Banshee platforms with zero modification required. The factory trigger breaks at approximately 6.5 pounds with minimal creep.
- Does the RIP Brace require ATF registration?
- As of my last ATF compliance review in January 2024, pistol braces remain in regulatory limbo. The Banshee ships as a pistol, but current interpretations suggest shouldering it may constitute manufacturing an SBR. Consult legal counsel before deployment—I recommend Silencer Shop's trust services for NFA items.
- How long does shipping take to FFL dealers?
- Ironclad Armory processes orders within 2 business days, with ground shipping adding 3-5 days transit time. All firearms ship signature-required to your chosen FFL holder. My last test purchase arrived at my Bozeman FFL in 4 business days total.
- Can I mount a suppressor on the 1/2x28 threads?
- The threads accept any standard 5.56 suppressor with 1/2x28 mounting, but the gas system may require adjustment. My Surefire SOCOM556-RC2 required adding a H3 buffer to reduce gas blowback. Plan on $150-200 in tuning parts for optimal suppressed operation.
- Does it work with Gen 3 PMAGs?
- It functions flawlessly with Magpul PMAG Gen 2 and Gen 3 magazines, though I've had occasional failure-to-lock issues with some metal USGI mags. The magwell is mil-spec dimensionally, accepting any STANAG-pattern magazine without modification.