The CMMG Fastback Receiver Extension (MPN 55CA93E) is a mil-spec diameter buffer tube built for AR-15 platform builds.

Key Specifications

• Mil-spec diameter for compatibility with mil-spec stocks and buffer components
• Part of CMMG’s Fastback receiver extension line
• Fits standard AR-15 lower receivers
• Manufactured by CMMG

Frequently Asked Questions

Is this mil-spec or commercial diameter?
Mil-spec diameter, so it pairs with mil-spec stocks, buffers, and springs.

What platform does it fit?
Standard AR-15 lower receivers.

Does it include a buffer and spring?
No, this listing is the receiver extension (buffer tube) only.

Buy the CMMG Fastback Receiver Extension

Complete your mil-spec buffer system with this receiver extension from CMMG. Ships fast from Lubbock, TX, part of our AR buffer system lineup.