CMMG Banshee Mk4 Pistol .300 AAC Blackout 8″ 30rd
About this product
The CMMG Banshee Mk4 Pistol in .300 AAC Blackout is a purpose-built short-barreled firearm platform designed for suppressed applications and close-to-mid-range engagement. It leverages the Mk4 AR pattern with a piston-driven radial-delay blowback system to manage the energetic demands of the .300 BLK cartridge from an 8-inch barrel. This configuration avoids the dwell-time and gas-pressure compromises inherent in traditional direct-impingement AR-15s when shortened.
What is the CMMG Banshee Mk4 used for?
The Banshee Mk4 is a high-performance suppressor host and urban/vehicle defensive tool. Its 8-inch barrel is the optimal length for the .300 Blackout cartridge, allowing full powder burn for both supersonic and heavy subsonic rounds while maintaining a compact 22.5-inch overall length. This makes it ideal for discrete carry in a vehicle or for home defense when paired with a suppressor, where its 66-ounce weight stabilizes rapid shots during high-stress scenarios.
How does the CMMG Banshee Mk4 compare to a pistol-caliber carbine like the CZ Scorpion?
The Banshee Mk4 delivers significantly more terminal energy and effective range than 9mm PCCs like the Stevens 334 Rifle in .308 Winchester. While a 9mm PCC is simpler and cheaper to feed, the .300 BLK from this platform hits with over 1,200 ft-lbs of muzzle energy with supersonic loads, versus roughly 400 ft-lbs from 9mm, making it decisively better for barrier penetration and ethical hunting of medium game under 150 yards where legal.
What does it weigh and what are the dimensions?
This pistol weighs 4.125 pounds (66 ounces) unloaded and measures 22.5 inches from muzzle thread to the end of the receiver extension tube. The 8-inch barrel features a 5/8"-24 thread pitch, the standard for .30 caliber muzzle devices and suppressors. The CMMG EML7 M-LOK handguard provides 7 inches of accessory real estate, and the unit ships with one 30-round PMAG.
Who is this NOT for?
This is not for a first-time AR buyer or someone seeking a low-cost plinker. The .300 AAC Blackout ammunition costs nearly three times that of 5.56mm NATO, and the platform's design is optimized for a specific, suppressed role. If your primary use is unsuppressed range time beyond 200 yards, a classic 16-inch rifle in 5.56 will be more practical and economical.
What's in the box?
You receive the complete pistol, one 30-round Magpul PMAG, a CMMG linear compensator installed on the 5/8"-24 threads, ambidextrous safety and bolt release, and the manual. Notably, it does not include iron sights, optic, suppressor, or a sling—essential additions that will add a minimum of $300-$1000 to your initial outlay.
Is the CMMG Banshee worth it at $1,384.99?
At this price, the Banshee Mk4 justifies its cost through its specialized radial-delay blowback operating system and suppressed-duty construction. You are paying for a mechanically superior solution to the short-barrel .300 BLK problem compared to a pieced-together AR pistol. If your use case involves a tax-stamped suppressor and you demand reliable cycling with subsonic ammunition, this is a turn-key solution that avoids the tuning and gas-block adjustments often required with DI guns.
Specs at a glance
Video review
Pros & cons
What works
- Weighs 66 oz (4.125 lb) — balances well for rapid target transitions
- Radial-delay blowback system virtually eliminates gas-in-face when suppressed
- 8-inch 4140 CM barrel is optimal length for .300 BLK powder burn
- Ambidextrous controls included — no need for aftermarket parts
Trade-offs
- Proprietary BCG and upper — limits aftermarket bolt/barrel swaps
- No sights included — adds $80-$400 for a basic optic or irons setup
- .300 BLK ammo averages $0.85/rd — 3x the cost of 5.56mm for practice
- Online Only — cannot handle before completing FFL transfer
Expert review
Key attributes
| upc | 810144724119 |
| manufacturer | CMMG |
| manufacturer part number | 30A240FAB |
| action | Semi-Auto |
| barrel length | 8" |
| caliber/gauge | .300 AAC Blackout |
| capacity | 30 + 1 |
| color | Black |
| length | 39.7500 |
| model | Banshee |
| number of magazines | 1 |
| safety | CMMG Zeroed 60/90 Degree |
| shipping weight | 9.05 |
| sights type | NONE |
| state restriction (il) | NO SALE TO ILLINOIS PICA |
| state restriction (or) | NO SALE TO OREGON |
| 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 parts?
- The lower receiver and fire control group are mil-spec AR-15 compatible. The upper receiver, bolt carrier group, and barrel are proprietary to CMMG's radial-delay blowback system and are not interchangeable with standard DI AR-15 components. The handguard uses a proprietary barrel nut but accepts any M-LOK or Picatinny accessories.
- Does this work with a SilencerCo Omega 300 suppressor?
- Yes, it is an excellent host. The 5/8"-24 muzzle threads are direct-thread compatible with the Omega 300 and most .30 caliber rifle suppressors. The radial-delay system reduces port pressure, which minimizes blowback and gas-to-face when suppressed, a significant advantage over direct-impingement ARs in this configuration.
- How long does shipping take to an FFL?
- Ironclad Armory processes and ships in-stock firearms within 1-3 business days. Transit time depends on your selected carrier and destination, typically adding 3-7 business days. Your chosen FFL must then process the transfer, which can take an additional 24-48 hours. Always contact your FFL with the tracking number before pickup.
- Can I return it if I don't like how it handles?
- No. Per federal law and Ironclad Armory's policy, firearms transfers are final upon completion at your FFL. We strongly recommend handling a similar model at a local dealer or range before purchasing. We only accept returns for un-fired firearms with verifiable manufacturer defects, which are handled through the manufacturer's warranty, not as a store return.