An AR-15 rifle build kit gathers the major components for a 16″ rifle into one package — barreled upper, handguard, muzzle device, bolt carrier group, charging handle, gas system, buffer tube, stock, grip, and a lower parts kit. Kits are offered with an 80% lower receiver or without a lower (upper and parts only), so you can buy the whole build or just the parts you still need.

Choose from .223/5.56, 300 Blackout, 7.62×39, and 9mm, in black and a range of color finishes. Use the filters to sort by caliber, handguard, and color.

AR-15 Rifle Build Kits

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Choosing an AR-15 Rifle Build Kit

A build kit saves you sourcing each part separately and keeps the finish matched. The main thing to check before you buy is whether the kit includes a lower — and whether it's assembled. Here's how to read them.

With or without an 80% lower

Kits come two ways. "With 80% lower" kits include an unfinished 80% lower receiver, so you get everything for the build and finish the lower yourself. "No lower" kits include everything except the lower — choose these if you already have a finished or stripped lower. Check the product title and listing for which one you're ordering.

What's in the kit

A complete kit includes a barreled upper assembly (barrel, handguard, muzzle device, bolt carrier group, charging handle, gas block, and gas tube), plus a buffer tube, stock, pistol grip, and lower parts kit. "With lower" kits add an 80% lower receiver. Kits do not include sights or optics — add your own. Exact contents vary by kit, so confirm the included-parts list on each product page.

Caliber options

Build kits are stocked in .223/5.56, 300 Blackout, 7.62x39, and 9mm (AR9). Match the kit's caliber to your intended use — 5.56 for general-purpose, 300 Blackout for suppressed and short-barrel builds, 7.62x39 for cheaper steel-case shooting, and 9mm for a pistol-caliber carbine.

Barrel and finish

Most kits use a 16" barrel in 4150 chrome-moly-vanadium steel with a nitride finish and M4 feed ramps, in common twist rates (1:7 or 1:8). Handguards are free-float Keymod or M-LOK in 10"–15" lengths. Finishes include black plus Cerakote colors — FDE, OD Green, Tungsten Grey, Burnt Bronze, Titanium Blue, Zombie Green, Pink, and Purple.

Assembled vs. unassembled

Some kits ship with the upper assembled; others are unassembled so you put the upper together yourself. The product title notes which. Assembled saves time; unassembled is a hands-on option and lets you inspect each part as you build.

Frequently Asked Questions

What's included in an AR-15 rifle build kit?

A barreled upper assembly (barrel, handguard, muzzle device, bolt carrier group, charging handle, gas block, gas tube), plus a buffer tube, stock, pistol grip, and lower parts kit. "With lower" kits also include an 80% lower receiver. Exact contents vary by kit — check the listing.

Do these kits include sights or optics?

No. AR-15 rifle build kits do not include iron sights or an optic — you add your own sighting system. This keeps the kit cost down and lets you choose the optic that fits your build.

What's the difference between a "with lower" and "no lower" kit?

A "with 80% lower" kit includes an unfinished 80% lower receiver along with the rest of the build. A "no lower" kit includes everything except the lower — pick that if you already have a lower to use.

What calibers are available?

.223/5.56, 300 Blackout, 7.62x39, and 9mm (AR9). Each has its own subcategory so you can filter to the caliber you're building.

Do you need an FFL to buy a rifle build kit?

It depends on how a kit is configured and where you live, and the rules around unfinished receivers and kits continue to evolve. Confirm the current federal and state requirements and how a specific kit ships before ordering. This page is general information, not legal advice.