Calibers: 5.56mm, 22 ARC, 6mm ARC, 6.5 Grendel, 300 BLK, 9mm, 350 Legend. AR-based system a with a more traditional rifle layout. Fixed stock, lack of a vertical pistol grip, muzzle brake rather than a flash hider. Legal in 47 states while still using detachable mags. Not legal in New York, Illinois, and Washington state at introduction. Comes standard with Magpul SGA 870 stock. Lower accepts Remington 870 aftermarket stocks. Takes standard AR mags. Crossbolt safety, reversible for left- or right-hand use. Oversized bolt catch, ambidextrous magazine catch, CMMG’s ZEROED Drop-In Trigger. BR4 lower is fully compatible with all CMMG Mk4-compatible Dissent upper groups. Barrels: 14.5″ with pinned-and-welded muzzle brake for overall barrel length of 16.1″ and 16.1″ plus muzzle brake. Slick-side upper without forward assist, brass deflector block, reversible non-reciprocating charging handle, full-length M-LOK handguard. Cerakote colors include Armor Black, Sniper Grey, Charcoal Green, Coyote Tan, Midnight Bronze, Titanium, Tungsten. Ships with two 10-round magazines. Introduced mid-2024.