CMMG 55CA646 Rifle Receiver Extension/Stock Kit – AR-15 Platform

The CMMG Rifle Receiver Extension/Stock Kit provides a complete solution for building or upgrading AR-15 rifles with a fixed stock configuration. This kit delivers a stable shooting platform that eliminates movement and enhances consistency, making it ideal for precision shooting applications where a solid cheek weld and repeatable positioning matter most.

This complete kit includes a rifle-length receiver extension (buffer tube), castle nut, and end plate—everything needed for installation of a rifle-length fixed stock. The receiver extension is manufactured to mil-spec dimensions ensuring compatibility with standard AR-15 lower receivers and rifle stocks. Constructed from durable steel with a phosphate finish for corrosion resistance. Installation requires standard armorer's tools and is straightforward for builders familiar with AR-platform assembly.

• Type: Rifle Receiver Extension Kit
• Compatible Firearms: AR-15 platform rifles
• Material: Steel
• Finish: Phosphate
• Adjustable: No (fixed rifle-length configuration)
• Installation: Requires armorer's wrench and basic tools
• Kit Includes: Receiver extension, castle nut, end plate