The CMMG Resolute 100 Mk57 Complete Upper Receiver is chambered in 5.7x28mm and features the radial delayed blowback mechanism. Build your own 5.7×28 AR-15 style rifle without breaking the bank. This AR-15 complete upper is designed for use with the dedicated lower but is now compatible with standard AR-15 lowers when used with the CMMG 5.7 magazine conversion kit. The barrel is made from 416 stainless steel and salt bath Nitride finished for extreme durability. This is a radial delayed blowback rifle, so there is no need for a gas block or gas tube making for an extremely simple and reliable system. The 15” RML handguard features M-LOK slots for attaching accessories and features a top picatinny rail that sits flush with the flat top upper receiver. The CMMG Mk57 Resolute 100 AR-15 upper receiver is perfect for your next unique build.
- 16” barrel chambered in 5.7×28
- Machined from 416 stainless steel and Nitride finished
- A2 flash hider
- Radial delayed blowback
- 15” RML M-LOK handguard
- Mil-Spec charging handle
- 7075-T6 aluminum receiver
- Black hardcoat anodized
- Weight: 4 lbs. 6 oz.
The upper receiver is forged from 7075-T6 aluminum and features a hardcoat anodized black. It comes fully assembled with a bolt carrier group, standard charging handle, and A2 flash hider.
A leading manufacturer of AR-15 rifles, kits, and accessories, CMMG Inc. was established in 2002. Constantly pushing the edge, CMMG strives to develop and improve bringing you a product lineup that is second to none.