Mil Spec AR 10 Butt Stock Build Kit

About this product

This is Combat Armory's Mil-Spec AR-10 buttstock build kit, a complete buffer-tube-and-stock assembly sized for the .308/AR-10 pattern rather than standard AR-15 dimensions. Combat Armory sells this direct through its own site, which is where the current $24.99 price was confirmed — a markdown from the regular $69.99 listed price.

What's included in an AR-10 buttstock build kit like this?

A kit in this category is built around a hard-anodized aluminum mil-spec buffer tube, a steel end plate, castle nut, carbine buffer, and carbine-length buffer spring, paired with a six-position mil-spec M4-style carbine stock and a recoil-reducing butt pad. Together these parts give a builder everything needed to finish out the rear of an AR-10 pattern lower beyond the receiver itself, without having to source each buffer tube component separately.

Why does AR-10 buttstock hardware differ from AR-15 parts?

The .308/AR-10 platform uses a longer buffer, spring, and buffer tube than the 5.56/AR-15 platform to handle the larger cartridge and heavier bolt carrier group, so AR-15 buttstock kits are not interchangeable with AR-10 pattern lowers even though the stocks can look similar side by side. Confirm your lower is a genuine .308/AR-10 pattern receiver before ordering, since fitment across different AR-10-style manufacturers can vary more than it does on the more standardized AR-15 platform.

Does this ship through an FFL?

No. A buttstock and buffer tube kit is a parts accessory, not a firearm, so it ships directly to your address with no FFL transfer required, regardless of what platform you're building it onto.

Does a collapsible stock affect California compliance on an AR-10 build?

A six-position adjustable stock by itself isn't the feature that triggers California's assault weapon classification — that law is primarily about the combination of a detachable magazine with certain features on a semi-automatic centerfire rifle, and requirements can differ for featureless or fixed-magazine configurations. Confirm current California build requirements for your specific .308/AR-10 lower and overall configuration with your FFL or a knowledgeable gunsmith before finishing the build.

For builders assembling an AR-10 pattern rifle from separate parts rather than buying a complete gun, buffer tube and stock kits like this one are typically one of the last mechanical pieces needed after the lower parts kit and upper are sorted out, since the stock assembly bolts directly onto the rear of the completed lower receiver. Installation is straightforward with basic armorer's tools — a castle nut wrench and an action block or vise block to hold the lower steady — and doesn't require gunsmithing beyond correctly torquing the castle nut against the end plate.

Combat Armory sells a comparable kit sized for AR-15/AR9 platforms as well, so double-check the listing specifically references .308/AR-10 dimensions before ordering if you're working across multiple builds, since a mismatched buffer tube simply won't fit an AR-10 receiver extension thread pattern correctly. At this price point, a mil-spec kit like this is one of the more economical ways to finish a home-built AR-10 lower compared to buying a premium billet stock system, and the recoil-reducing pad is a genuinely useful addition given how much stouter felt recoil is on a .308-class semi-auto compared to a 5.56 AR-15 with the same basic layout. Builders who already own AR-15 tools will find the assembly process nearly identical, just scaled to the larger AR-10 buffer tube diameter and length.