Winchester's release of the incredible 350 Legend cartridge set the shooting world on fire, thanks to the powerful specs behind this new round. CMMG was one of the first companies out of the gate to offer a full-fledged AR-15 built around the new cartridge, and now the company offers complete Mk4 Resolute upper receivers chambered for the new round. The CMMG Mk4 Resolute upper receiver shown here mates with any mil-spec lower receiver and comes with all the features you need to rock and roll with this new round, including a 4140CM barrel with a medium taper, a carbine-length gas system and a 15-inch M-LOK handguard. Barrel length: 16.1 inches Overall length: 25.2 in Mfg: Cmmg