The CMMG Dissent Br4 (brand part no. 94AC80FAB) is a 9mm pistol-caliber carbine built on CMMG’s Radial Delayed Blowback system, pairing classic rifle ergonomics with a fixed-ejector action tuned specifically for pistol-caliber reliability. The billet Br4 lower runs CMMG’s 9mm conversion magazines and still accepts other STANAG-pattern magazines if you swap to a different Mk4 Dissent upper. A 16.1-inch barrel keeps the Dissent Br4 rifle-length compliant while the CMMG ZEROED muzzle brake tames recoil for faster follow-up shots. Built for range use, home defense, and anyone who wants AR-15 ergonomics without the added cost of 5.56 ammunition, the Dissent Br4 gives you carbine handling in a lighter, softer-shooting package.

Key Specifications

• Chambered in 9mm, the Dissent Br4 runs on CMMG’s dedicated 9mm conversion magazines.
• CMMG’s Radial Delayed Blowback operating system uses a fixed ejector to smooth out recoil compared to a standard blowback PCC.
• The 16.1-inch barrel uses a 1:10 twist rate matched to common 9mm bullet weights.
• A 4140CM steel barrel with SBN finish resists wear and corrosion under heavy range use.
• The CMMG ZEROED muzzle brake threads onto a 1/2×28 muzzle to cut recoil and muzzle rise.
• The DISSENT PCC 7075-T6 aluminum upper receiver delivers a rigid, precisely machined platform for reliable cycling.
• The Br4 billet 7075-T6 aluminum lower receiver is machined, not cast, for tighter tolerances and a smoother trigger feel.
• The CMMG 15-inch proprietary M-LOK handguard is free-floating and provides ample rail space for lights and optics.
• The reversible Dissent side-charging handle lets you run the carbine comfortably from either shoulder.
• CMMG’s ZEROED drop-in single-stage trigger gives a clean, consistent break for faster, more accurate follow-up shots.

Frequently Asked Questions

What caliber does the Dissent Br4 shoot? It’s chambered in 9mm and runs on CMMG’s dedicated 9mm conversion magazines.

Is the muzzle threaded for a suppressor? Yes, the barrel is threaded 1/2×28 so the included ZEROED muzzle brake can be swapped for a suppressor.

Can I run a different upper on this lower? Yes, the Br4 lower accepts other STANAG-pattern magazines, so it can run a different Mk4 Dissent upper if you switch platforms.

Buy the CMMG Dissent Br4 9mm Carbine

The Dissent Br4 gives you CMMG’s smoothest-shooting PCC platform in a billet-lower package built for range days, home defense, and anyone who wants rifle ergonomics without full-size rifle recoil. Its Radial Delayed Blowback system and ZEROED trigger make it easy to shoot fast and stay on target. Order it from our Lubbock, Texas gun shop for fast, insured shipping to your FFL, and browse CMMG‘s full lineup of AR rifles.