CMMG Resolute Mk57 5.7x28mm Complete Upper Receiver - 16.1in - Personal defense calibers like 5.7x28mm have become a big thing in the last few years, and if you're looking for PDW ballistics and the classic style and balance of a carbine then you're in luck. Combine this RESOLUTE complete upper receiver with either our Mk57 Lower or a standard AR15 lower group and you'll be ready to hit the range! Available in seven different Cerakote finishes, all CMMG Upper Groups come complete with bolt carrier group and ZEROED ambi charging handle. Features Made in the USA ; ZEROED AR15 Polymer Dust Cover; ZEROED AR15 Ambi Charging Handle; ZEROED Muzzle Brake;