TFB Review: CMMG Mk57 5.7x28mm Conversion Kit

By Rusty S.

The CMMG Mk57: A 5.7 upper that works CMMG continues on the 5.7×28 revival path. Last year, we reviewed CMMG’s FiveSeven magazine compatible 5.7×28 Banshee. Further reinforcing the 5.7×28 revival is CMMG’s new Mk57 Upper Conversion kit for standard AR lowers. Of most import is the fact that CMMG developed a 40 round 5.7×28 magazine […]

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Source:: The Firearm Blog