LBE Unlimited AR-15 Mil-Spec Buffer Tube Kit with Recoil Spring, Castle Nut, Receiver End Plate, and Buffer - Brown Finish

The LBE Unlimited AR-15 mil-spec buffer tube kit is a complete carrier system for building or completing the rear end of your AR platform rifle. This kit bundles everything you need in one package: a six-position mil-spec diameter buffer tube, carbine-length recoil spring, standard carbine buffer, receiver end plate, and castle nut. Whether you're assembling an upper receiver, swapping out a worn system, or finishing a lower receiver build, having all the pieces together cuts down trips to source parts individually and ensures compatibility across components.

LBE Unlimited has built a reputation for manufacturing mil-spec compliant parts stateside, and this kit reflects that commitment to meeting actual military specifications rather than loose interpretations. The brown finish blends durability with a classic look that works across modern and traditional AR builds. The six-position design lets you dial in your cheek weld and sight picture without major adjustments between shooting positions or gear swaps.

This is a no-frills, function-first approach to a fundamental AR system—the kind of kit that's equally at home on a rifle destined for the range, the field, or a defensive role. If you're building from a bare lower or maintaining an existing platform, this removes the guesswork of matching spring rates and tube diameters.

Key Features

• Complete buffer tube assembly kit—tube, spring, buffer, end plate, and castle nut included
• Mil-spec diameter buffer tube with six adjustable positions
• Carbine-length recoil spring and standard carbine buffer
• Brown finish
• US-made components by LBE Unlimited

Specifications

Frequently Asked Questions

What's included in this AR-15 buffer tube kit?

The kit includes a six-position mil-spec diameter buffer tube, carbine-length recoil spring, standard carbine recoil buffer, receiver end plate, and castle nut. It's a complete system, so you have everything needed to assemble or replace a buffer tube assembly on your AR platform.

Will this buffer tube kit work with my AR-15 lower receiver?

Yes. This is a mil-spec diameter buffer tube, which is the standard specification for AR-15 and AR-10 platform lower receivers. It will fit any mil-spec lower.

What's the difference between the six positions on this buffer tube?

The six positions allow you to adjust where your stock seats on the tube. This lets you fine-tune cheek weld, sight picture height, and overall length of pull depending on your shooting position, optic setup, or body armor configuration.

Is this kit compatible with any stock, or does it require a specific model?

The kit provides the buffer tube itself, but any AR-15 stock designed for a mil-spec buffer tube will work with it. You'll need to source your stock separately if you don't already have one.