P80 Kit

An 80% lower is a partially completed firearm frame that requires machining and assembly before it’s functional—ideal for builders who want full control over their pistol’s specs. Polymer80’s P80 kits stand out because they’re engineered for durability (glass-filled nylon, not cheap plastic) and compatibility with OEM Glock/Sig parts. These aren’t range toys; they’re for competitors, concealed carriers, and anyone who needs a no-BS platform that won’t fail when it counts. No FFL transfer needed—yet.

What’s in a P80 build kit
Frame-only kits include the 80% lower, jig, and drill bits—you source the LPK, slide, and barrel. Complete kits add everything but the slide (lower parts kit, UPK, recoil spring, sometimes a mag). Either way, you’ll need a Dremel or drill press, calipers, and patience. Pro tip: Buy a spare locking block (G17/G19 kits sometimes need fitting). Avoid eBay UPKs; stick to OEM or proven aftermarket like AIM Surplus.

Choosing the right frame
Match the P80 model to your slide: PF940C fits Glock 19 Gen3 slides (compact), PF940V2 for G17 Gen3 (full-size), PF940SC for subcompact G26. Big-bore shooters want the PF45 (G21 .45 ACP). Slim-line? PF9SS mirrors the G43. For Sig fans, the PF320PTEX takes P320 slides but requires more milling. Double-check rail specs—some aftermarket slides need adapter keys. If you’re running a comp, go V2 for the extra weight.

Legal status
Federal law (as of 2025) still allows 80% lowers without serialization or background checks, but ATF Rule 2021R-05F tries to redefine them as firearms. State laws vary: CA, NY, NJ, WA, RI, HI, NV, OR, CO, and DE ban or restrict them. We won’t ship to restricted states—period. Verify your local laws before buying. Tennessee? You’re clear, but serialize if you ever plan to sell.

Building tips for first-timers
Drill pin holes first—go slow with lube to prevent polymer melting. Use the end mill for the recoil channel; uneven depth causes cycling issues. Break all sharp edges with 400-grit sandpaper. Dry-fit the slide before final assembly—if it binds, check the rear rail module alignment. Common mistakes: over-drilling pin holes (measure twice), skipping deburring (cracks start there), and forcing parts (if it won’t seat, something’s wrong).