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The CMMG AR15 Carbine Receiver Extension and M4 Stock Kit includes the essentials for your AR lower build. The M4 buttstock is a lightweight, durable design. Combine this kit with your choice of Lower Parts Kit to complete your lower group. All CMMG products are backed by our Lifetime Quality Guarantee. Kit Includes: - 6-position M4 Buttstock Assembly - CMMG 6-position mil-spec Receiver Extension (Buffer Tube) - Buffer Tube Castle Nut - Receiver Endplate - Carbine Buffer - Carbine Action Spring
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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 overview of AR-15 buffer systems, covering carbine vs. rifle receiver extensions, buffer weights, springs, and how these parts affect cycling and recoil.
5 min read