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Our updated billet AR-15 billet 80% lower with a quality lower build kit. Grab a quality, mil-spec lower assembly kit built to pair with your new 80% lower and save! This kit contains all components required to assemble the lower half of your custom AR-15 build in one kit. Just finish the lower, put it…
No AR-15 build is complete without a butt stock assembly – and this one comes with all you need: Black FIRE/SAFE engraved 80% lower, lower parts kit, butt stock, buffer tube assembly. One (1) Black FIRE/SAFE 80% Lower Receiver: FIRE/SAFE Engraved Color: Anodized Mil-Spec Black Quantity:1 Forged 7075-T6 Aluminum Broached Magwell 100% Made in the USA Sold…
Got your mind set on building your own AR10 Rifle? Then check out this lower assembly that features a .308 80% lower crafted from 7075-T6 aluminum billet and anodized black. It also includes a lower parts kit that has been laser cut and polished for a smooth trigger pull as well as a 6-position buffer…
Got your mind set on building your own AR10 Rifle? Then check out this lower build kit that features a .308 80% lower crafted from 7075-T6 aluminum billet and anodized black. It also includes a lower parts kit that has been laser cut and polished for a smooth trigger pull. Billet .308 80% Lower Receiver:…
Start your next AR build by killing two birds with one stone. Get your 80% lower and your lower parts kit all in the same place in one fell swoop. This bundle includes both. You get a 7075 T6 forged aluminum 80% lower and a mil-spec lower parts kit that’s had its interacting surfaces polished…
Our new and improved billet AR-9 80% lower, with a quality lower parts kit! Grab our new and improved AR-9 80% lower with a mil-spec lower parts kit thrown in, and save on this bundle! Featuring an updated design with better aesthetics, a new magazine catch and ejector fasteners, our second generation AR-9 80% lower…
Our updated AR-15 billet 80% lower now paired with a quality lower parts kit. Grab a quality, mil-spec LPK to pair with your new 80% lower and save! We’ve bundled a quality parts kit with our new billet lower to offer a convenient 2-for-1 package that makes your custom AR-15 build easier and more affordable….
Our new and improved billet AR-9 80% lower, in a full lower build kit! Our new and improved AR-9 80% lower now comes available with a full lower build kit! Includes an LPK, 9mm buffer kit, and SBA-3 brace! Featuring an updated design with better aesthetics, a new magazine catch and ejector fasteners, our second…
If you’re finishing the “bottom half” of your AR, a complete lower assembly kit is the fastest, most reliable way to get from parts on the bench to a ready-to-pin receiver.
Our kits bundle the components you’d otherwise hunt down one-by-one (like the lower parts kit, buffer tube system, stock or brace, and small parts) so your lower is ready to meet a barreled upper with zero guesswork.
Whether you’re building your first AR-15 in 5.56/.223, a compact AR-9, or an AR-10 for longrange shooting, you’ll find proven, mil-spec options here.
Our lower assembly kits provide the full LPK (trigger, hammer, disconnector, safety, bolt catch/release, mag catch, takedown/pivot pins, detents, springs, and hardware), plus a carbine buffer tube, buffer, recoil spring, end plate, castle nut, and either a buttstock or pistol brace.
That means your serialized stripped lower (or completed 80% lower) can be fully assembled into a functional receiver that’s ready for an upper and BCG. Upgrades in select kits include enhanced triggers, Magpul® furniture or pistol-ready SBA3-style braces.
A complete upper assembly is the “other half” to your lower assembly. Grab an AR-15 upper, AR-10 upper, or AR-9 upper based on your assembly kit’s caliber, and you’ll have everything needed to finish your new rifle or pistol!
AR-15 (5.56/.223 & 300 BLK): These kits include mil-spec LPKs and carbine buffer systems that work with all AR-15 lowers.
AR-9 (9mm): Choose an AR-9 assembly kit to match your PCC build. Note the mag catch and some small parts differ from the AR-15.
LR-308/AR-10 (.308 Win): Use LR-308/AR-10 LPKs and buffer components. Note that these are not cross-compatible with AR-15 lowers; they work with the larger AR-10 lower and upper receivers.
If you’re unsure which platform you’re building, check your upper or planned caliber and match the kit accordingly. Need further assistance? Our expert customer service is here to help! Call us or email us here.
Fewer mistakes: All required parts are in one box, reducing frustrating guesswork when it comes to build.
Compatibility: Stop decoding part lists. Our kits guarantee everything works together. Just assemble and go.
Consistent fit: Our kits are built with mil-spec receivers and quality parts to ensure reliability and accuracy.
Upgrade later: An assembly kit provides the bones for upgrading your AR later, reducing upfront costs.
We’ve got you covered! Use our step-by-step install guide to build your lower assembly.
Deciding on what specifications or parts to use for your custom AR? We’ve got detailed build guides for every caliber and platform to help you pick out the right stuff:
The Ultimate AR-15 Build Guide
The 80% Lower Compatibility Guide
A: Every lower assembly includes a lower parts kits, buffer tube, buffer, recoil spring, end plate, castle nut, and stock or brace.
A: Under federal law, no. Our lower assembly kits include an 80% lower sold without jigs or tooling. Under ATF’s 2022 frame or receiver rule, which the Supreme Court upheld in Bondi v. VanDerStok in March 2025, a receiver blank that hasn’t reached the point where it can be readily completed isn’t a firearm. Some states treat these kits as firearms, and we can’t ship to those states. See our shipping restrictions for more information.
A: These platforms are identical except for one small difference in the shapes of the upper and lower receivers. See our guide for more info: The AR-10 vs. LR-308.
A: Both use the same lower parts kit, including the trigger, hammer, disconnector and safety, pistol grip, and buffer system. The AR-9 uses a heavier buffer, and its lower receiver uses GLOCK magazines with a custom magazine catch and ejector.
A: The lower assembly kit provides the bottom half of your build. You can complete your AR with a complete upper assembly. Note the lower assemblies’ included 80% lower is unfinished. It must be fabricated before installation of components.
Some states have banned 80% lowers and certain firearm parts, or have otherwise restricted the sale and ownership of the products we sell. If you cannot add a lower assembly to your cart and check out, it may be because we cannot sell our kits in your state. Please check our Shipping & Return Policy before placing an order (See Restrictions).
Your build awaits!
DISCLAIMER: If you are new to the world of DIY gun building, you likely have a lot of questions and rightfully so. It’s an area that has a lot of questions that, without the correct answers, could have some serious implications. At 80-Lower.com, we are by no means providing this content on our website to serve as legal advice or legal counsel. We encourage each and every builder to perform their own research around their respective State laws as well as educating themselves on the Federal laws. When performing your own research, please be sure that you are getting your information from a reliable source.
