The BCM Mil-Spec Buffer Tube Kit (brand part number BCM STOCK HARDWARE KIT) gives AR-15 builders everything needed to mount a collapsible stock in one box, built to genuine Mil-Spec dimensions rather than the looser commercial-spec tolerance some kits use. The kit centers on a 6-position Mil-Spec receiver extension, along with the receiver end plate, M4 castle lock nut, carbine action spring, and buffer that complete the system. Because everything ships together as a matched set, builders avoid the fitment headaches that can crop up mixing receiver extensions and buffers from different manufacturers. It’s a straightforward, no-guesswork way to get a reliable stock foundation on a new AR-15 build.

Key Specifications

• Includes a Mil-Spec 6-position receiver extension (buffer tube).
• Includes a receiver end plate.
• Includes an M4 castle lock nut.
• Includes a carbine action spring.
• Includes a buffer.
• Ships as a complete kit with all mounting hardware.
• Built to true Mil-Spec tolerances for GI-pattern lowers.
• Fits the AR-15 platform.

Frequently Asked Questions

What’s included in this kit? A 6-position Mil-Spec receiver extension, end plate, castle nut, action spring, buffer, and mounting hardware.

Is this true Mil-Spec or commercial-spec? True Mil-Spec dimensions, built to GI-pattern tolerances.

Buy the BCM Mil-Spec Buffer Tube Kit – with Buffer, Spring, and Hardware

Get a matched, no-guesswork stock foundation for your next AR-15 build. Order it from our Bravo Company Mfg / BCM lineup, part of our AR buffer system selection, at our Lubbock, Texas gun shop for fast, direct shipping.