The CMMG Banshee Mk4 (CMMG part no. 55AC20A-MB) is a 5.56 NATO AR-platform pistol built for shooters who want rifle-caliber performance in a compact, maneuverable package. Its 12.5-inch barrel balances velocity retention with a shorter overall footprint, and the included RIP brace gives you a stable, adjustable point of contact without the size of a full rifle. Finished in a distinctive bronze Cerakote, this Banshee doubles as a truck gun, home-defense pistol, or range companion. CMMG built the Mk4 platform on standard AR15 lower architecture, so it drops into the wider ecosystem of AR parts and accessories.

Key Specifications

• Chambered in 5.56 NATO/.223 Remington, one of the most versatile and widely available centerfire rifle cartridges.
• Runs a 12.5-inch barrel that keeps velocity high while trimming overall length for close-quarters handling.
• Ships with 30-round capacity standard-pattern AR magazines for a deep reserve of ready ammunition.
• Includes 1 magazine in the box so you can start shooting right out of the case.
• Overall length measures 39.6 inches with the RIP brace extended, staying compact for storage and transport.
• Features an ambidextrous safety selector for fast, natural manipulation from either shoulder.
• Ships optics-ready with no fixed sights, leaving the full-length top rail open for a red dot or LPVO.
• Runs in semi-auto only, cycling off a direct impingement gas system for reliable follow-up shots.
• Finished in bronze Cerakote for a distinctive look and added corrosion resistance over bare metal.
• Comes equipped with CMMG’s RIP brace, a stabilizing brace designed specifically for the Banshee lineup.

Frequently Asked Questions

Is the CMMG Banshee Mk4 optics-ready? Yes, it ships with no fixed sights and a full-length top rail so you can mount the red dot or optic of your choice.

What caliber does this pistol use? It is chambered in 5.56 NATO/.223 Remington, giving you access to a huge range of factory and reloaded ammunition.

Does it come with a magazine? Yes, one 30-round capacity magazine ships with the pistol.

Buy the CMMG Banshee Mk4 Pistol, 5.56 NATO, 12.5-Inch, Bronze

This Banshee pairs a proven AR platform with a caliber that never goes out of style, all in a size that fits in a backpack or truck console. The bronze Cerakote finish sets it apart from the sea of black rifles without sacrificing any of the durability shooters expect from CMMG. Order it from our AR pistols lineup at our Lubbock, Texas gun shop for fast, insured shipping to your FFL.