The CMMG AR-15 Carbine Receiver Extension and 6-Position M4 Stock Kit (CMMG part no. 55CA634) has the essentials for finishing an AR-15 lower. CMMG describes the M4 buttstock as a proven lightweight design that is extremely durable. The kit pairs it with a CMMG 6-position mil-spec receiver extension and a carbine buffer system. Add your choice of lower parts kit to complete the lower group.

Key Specifications

• The stock is an M4 buttstock assembly with six positions, a lightweight and durable design.
• The receiver extension is a CMMG 6-position mil-spec buffer tube.
• The buffer type is carbine, with a carbine buffer and a carbine action spring included.
• A buffer tube castle nut and receiver endplate are included.
• The kit is built for AR-15 lower builds, according to CMMG.

Frequently Asked Questions

What is in the kit? CMMG lists a 6-position M4 buttstock assembly, a 6-position mil-spec receiver extension (buffer tube), a buffer tube castle nut, a receiver endplate, a carbine buffer and a carbine action spring.

Do I need anything else to finish the lower? CMMG suggests combining the kit with your choice of lower parts kit to complete the lower group.

Buy the CMMG AR-15 Carbine Receiver Extension and 6-Position M4 Stock Kit

It covers the stock end of a carbine build in one box. See more gun parts kits from CMMG. Order from our Lubbock, Texas gun shop for fast, direct shipping.