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Lower Group for Resolute Mk57 in 5.7x28mm carbine or SBR. Cross-compatibility with magazines used in FN Five-seveN pattern. Available in Cerakote finishes. Includes: Mk57 Lower Receiver, CMMG RipStock, ZEROED Pistol Grip, ZEROED Ambi Safety (60°/90°), ZEROED AR15 Bolt Catch, Mil-Spec Trigger. Mk57 lowers designed for use with CMMG 5.7x28mm Radial Delayed Blowback uppers only. Lifetime Quality Guarantee.
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A comprehensive overview of every major component in an AR-15 build—including what's inside bolt carrier groups and parts kits—organized by assembly for new builders.
12 min read
Guide
A neutral guide to component strategies for left-handed shooters, left-eye dominant right-handed shooters, and those managing eye/hand dominance mismatches. Covers ambi uppers, charging handles, gas system tuning, and real-world tradeoffs.
6 min read