Quickly becoming a fan favorite over the last several years 5.7x28mm has found favor with those looking for a fast lightweight round that offers excellent penetration at short ranges with minimal recoil. - The CMMG® Mk57 platform is designed exclusively to accept FN®* Five-seveN®* style magazines without sacrificing essential AR functionality like last round bolt hold open. Not only can you have the same round in your pistol and carbine but you can also use the same magazines for both! - When full-size rifles are too cumbersome and pistols/SBRs don’t deliver the long-range ballistic performance you need the CMMG RESOLUTE line of carbine length rifles is the answer. Fitted with the suite of ZEROED parts and accessories as well as our legendary RIPSTOCK the RESOLUTE is the rifle that’s never out of place. The new EML 15 handguard brings style to the next level. M-LOK® attachment slots are found where expected at the 3 6 and 9 o’clock positions as well as on top at 12 o’clock with the omission of a full-length Picatinny section found on our previous handguard. This reduces weight while the additional M-LOK section still gives shooters a place to mount those must-have accessories. With a range of choices just pick the caliber you need for the job and let your rifle do the talking. - Platform Mk57 - Caliber 5.7x28mm - Operating System Radial Delayed Blowback - Barrel Length 16.1 - Barrel Twist 1:9 - Barrel Contour MT - Barrel Material 4140CM SBN - Barrel Twist 1:9 - Muzzle Device CMMG ZEROED Muzzle Brake - Muzzle Thread 1/2 x 28 - Upper Receiver Billet 6061 T6 Aluminum - Lower Receiver Mk57 Forged 7075 T6 Aluminum - Hand Guard CMMG EML15 M-LOK - Finish Cerakote - Charging Handle CMMG ZEROED Ambi - Pistol Grip CMMG ZEROED Pistol Grip - Buffer Type Carbine - Receiver Extension CMMG 6 Position Fastback w/Ambi Sling Plate - Stock / Brace CMMG RipStock - Trigger Type ZEROED Drop-In - Trigger Guard Integrated - Safety Selector CMMG ZEROED 60/90 Degree - Magazine 20rd Promag - Weight 6.2 lbs - Length 32.5