The CMMG Banshee Mk4 Upper Group (brand part no. 46B965AAB) chambers the 4.6x30mm cartridge on an AR15-compatible platform, and CMMG was the first company to bring a 4.6x30mm firearm to the U.S. civilian market, continuing a tradition of innovation for shooters who want a light-recoiling, flat-shooting personal defense weapon unlike anything else on the AR platform. This Mk4 upper is designed to work with any standard AR15 lower receiver and CMMG’s own 4.6x30mm magazines, and it comes complete with a bolt carrier group and CMMG’s ZEROED accessories, including a ZEROED AR15 polymer dust cover, a ZEROED AR15 ambidextrous charging handle, and a ZEROED linear compensator. The 8-inch barrel is built from 4140CM steel with a salt bath nitride finish, an MT contour, and a 1:5.9 twist rate, chambered with a micro gas port location and a FourSix-specific .750 gas block. The billet 6061-T6 aluminum upper receiver is machined to mil-spec M16/M4 dimensions, and the whole assembly weighs approximately 3.2 pounds at an overall length of 16.5 inches, with a CMMG EML7 M-LOK handguard and a Cerakote standard finish.

Key Specifications

• Chambered in 4.6x30mm, a light-recoiling PDW cartridge.
• Barrel measures 8 inches with an MT contour and 1:5.9 twist.
• Barrel built from 4140CM steel with a salt bath nitride finish.
• Operates on a direct impingement system with a micro gas port.
• Threaded 1/2×28 and fitted with a CMMG ZEROED linear compensator.
• Upper receiver is billet 6061-T6 aluminum, machined to mil-spec M16/M4 dimensions.
• Includes a CMMG EML7 M-LOK handguard and ZEROED ambidextrous charging handle.
• Compatible with any standard AR15 lower receiver and CMMG’s 4.6x30mm magazines.
• Weighs approximately 3.2 pounds at an overall length of 16.5 inches.

Frequently Asked Questions

Will this upper work on any AR15 lower? Yes, it’s designed to work with any standard AR15 lower receiver, paired with CMMG’s dedicated 4.6x30mm magazines.

Does this upper come with a bolt carrier group? Yes, it ships complete with a bolt carrier group and CMMG’s ZEROED accessories.

What makes 4.6x30mm different from 5.56? It’s a smaller, lighter-recoiling PDW cartridge, giving a flatter-shooting, faster-handling platform than standard 5.56 in a similarly sized upper.

Buy the CMMG Banshee Mk4 Upper Group, 4.6x30mm, 8-inch, Black

Add a light-recoiling PDW upper to any standard AR15 lower. Order it through our CMMG lineup of AR15 uppers, and we’ll get it ready to ship as soon as it’s available from our Lubbock, Texas gun shop.