CMMG created the Resolute MK4 Rifle for people who won't accept for less than the best. The CMMG Resolute Mk4 Semi-Auto Rifle is a precision-built AR-15 platform capable of supreme accuracy during the repeated fire. There are many different calibers available, including 5.56x45mm NATO, 9mm, .350 Legend, 300 BLK, etc. Each Resolute Mk4 rifle has a 16-inch barrel (or 17-inch barrel for the .22LR model), and it is well-balanced, accurate, and maneuverable. The rifles feature a CMMG Ripstock, ambidextrous safety selector, and Cerakote receivers and handguard. Other features include a ZEROED stock, pistol grip, ambidextrous safety, and an extended magazine catch. The receiver features the company's patent-pending Radial Delayed Blowback action and is a forged 7075-T6 AL M4 upper with an AR-15 lower. The RDB has the same rotating locking lugs as the AR-15, but it uses a direct blowback action and has a lighter bolt-carrier group. To help with recoil reduction, the upper has a barrel with a threaded muzzle brake. The forend is compact and has M-LOK accessory attachment ports. Even with a huge optic attached, operating the bolt is effortless because of the ZEROED's ambidextrous charging handle. Whether you're looking to defend your family or want to perform at your very best at the range, this Mk4 AR-15 is built for action and tough use.