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RSR Stock #: CMMG57A405E-MB
Manufacturer Part #: 57A405E-MB
UPC: 810046239018

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CMMG, Resolut MK57, Semi-automatic Rifle, 5.7X28MM, 16.1" Barrel, Threaded 1/2x28, ZEROED SR Brake, Cerakote Finish, Midnight Bronze, 15" Free Float M-LOK Handguard, ZEROED Polymer Grip, CMMG RipStock, Manual Safety, 20 Rounds, 1 Magazine


WARNING: This product can expose you to chemicals including lead, which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to


"GLOCK” is a federally registered trademark of GLOCK, Inc. and is one of many trademarks owned by GLOCK, Inc. or GLOCK Ges.m.b.H.  Neither RSR Group, Inc. nor this site are affiliated in any manner with, or otherwise endorsed by, GLOCK, Inc. or GLOCK Ges.m.b.H.  The use of “GLOCK” on this page is merely to advertise the sale of GLOCK pistols, parts, or components.  For genuine GLOCK, Inc. and GLOCK Ges.m.b.H. products and parts visit

  • ZEROED Pistol Grip
  • ZEROED 60 degree/90 degree Ambi Safety
  • ZEROED AR15 Ambi Charging Handle
  • ZEROED AR15 Bolt Catch
  • ZEROED AR15 Polymer Dust Cover
  • ZEROED Muzzle Brake 5.56mm

Product Description

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!