The CMMG Banshee MK4 is a semi-automatic pistol built on the AR15 platform, chambered in the big-bore .338 ARC cartridge. It has a 10.5-inch barrel and a Midnight Bronze finish, and it is built to run both suppressed and unsuppressed while staying on the same AR15-pattern controls shooters already know. 
 

Key Specifications 

• Brand: CMMG 
• Model: Banshee MK4 
• Caliber: .338 ARC 
• Action: Semi Auto 
• Barrel Length: 10.5 in 
• Finish: Midnight Bronze 
   

Detailed Features 

• 10.5-inch barrel suits the compact Banshee MK4 pistol format 
• .338 ARC chambering is a big-bore option within the AR15-pattern platform 
• Purpose-built for the AR15-pattern platform, keeping controls and layout familiar 
• Midnight Bronze finish covers the receiver and handguard 
• Configuration supports both suppressed and unsuppressed shooting

CMMG's Banshee MK4 pistols in .338 ARC are aimed at owners who want more downrange energy than 5.56 or .300 Blackout in a similar-size AR-pattern pistol. Reaction to the cartridge itself is generally positive among owners who already run big-bore AR pistols, though some note that .338 ARC ammunition is less widely stocked than the more common calibers.

Handling feedback on the Banshee MK4 pistol format is mixed. The short 10.5-inch barrel keeps the gun compact and maneuverable, and owners running it suppressed like the balance, but shooters used to a longer sight radius sometimes find the pistol snappier to manage unsuppressed. The Midnight Bronze finish gets consistent compliments for looks and durability.

CMMG's build quality on the Banshee line is generally well regarded, with owners citing smooth cycling once the gun is broken in. The main complaint tracks the cartridge itself: buyers weigh the .338 ARC's terminal performance against the narrower ammunition selection compared to mainstream AR calibers.