Billet 80% Lower (Raw)

About this product

What is the FrameSmith Billet 80% Lower (Raw)?

The FrameSmith Billet 80% Lower (Raw) is a CNC-machined 80% lower receiver for building AR-15 and AR-308 platform firearms. This product serves as the unmarked, unfinished starting point for a custom rifle, pistol, or lightweight build, requiring final machining by the builder to reach 100% completion. It ships directly to the buyer without FFL transfer, serialization, or paperwork, as permitted by federal law for personal use.

What is the Billet 80% Lower (Raw) used for?

This receiver blank is used as the foundation for completing a custom AR-15 or AR-308 firearm. It's the first and most critical component in a build, onto which all other parts—like lower parts kits, buffer tubes, and uppers—are installed after the final fire control group pocket and trigger pin holes are milled. Builders typically pair it with a dedicated jig like the 80% AR-15 Easy Jig® Gen 1 or our .308 80% Lower – Billet for larger caliber builds.

How does the Billet 80% Lower (Raw) compare to a forged 80% lower?

The FrameSmith billet lower provides a measurable advantage in material consistency over common forged alternatives. Where forged receivers start with a hot-worked aluminum ingot, creating microscopic grain flow lines that can introduce slight dimensional variance, this billet receiver is machined from a single, solid 6061-T6 aluminum block, eliminating those flow lines. This results in a surface finish that measures 32-40 µin Ra (microinch roughness average) as-machined, compared to the typical 63-125 µin Ra of an as-forged surface, requiring less final polishing for builders pursuing a clean, precise aesthetic.

What does it weigh and what are the dimensions?

The lower weighs 7.2 ounces (204 grams) in its raw, unfinished state. Its critical dimensions align with mil-spec: a 0.925-inch wide magazine well, a 1.180-inch buffer tube thread boss diameter, and a total length from the rear takedown pin detent hole to the front hinge pin hole of 7.625 inches. The fire control group pocket is intentionally unmilled, presenting a 0.980-inch thick solid wall of aluminum at its thickest point for the builder to remove.

Who is this NOT for?

This product is not for first-time builders without access to a drill press, milling setup, or a compatible jig system. It requires specific, non-household tools; for guidance, consult our AR-15 80% Lower Receiver Jig & Tool Compatibility Guide. It is also unsuitable for anyone seeking a completed, serialized lower receiver ready for immediate parts installation, or for builders in states where possession or manufacture of unserialized firearms is prohibited.

What's in the box?

The box contains exactly one (1) raw, unfinished 6061-T6 aluminum billet lower receiver, packaged in static-dissipative foam. No tools, jigs, roll pins, springs, or other components are included. The product is presented precisely as-machined, with all protective sharp edges from the CNC process intact for the builder to deburr. This singular focus on the core component keeps the price point at $79.99, making it a dedicated starting point.

Is the Billet 80% Lower (Raw) worth it at $79.99?

Yes, it represents clear value for builders prioritizing material integrity and a clean starting canvas. At $79.99, it is priced $15-$25 higher than many basic forged 80% lowers, but that premium buys the dimensional stability of billet aluminum, a pre-threaded bolt catch pin hole (a 4-6 minute time savings), and the absence of forging marks that can telegraph through thin anodizing. For a builder investing $800+ in a complete rifle, this $80 foundation ensures subsequent parts fit with minimal tolerance stacking, a measurable long-term advantage.