Pistol builds: frames, slides and parts, the legal way

Building or upgrading a Glock-pattern pistol is one of the most popular projects in the gun world. You can choose your own slide cut, barrel, trigger and sights, and end up with a pistol that fits you exactly. This guide explains how to do it legally in 2026 and what to look for in each part. The name of this store comes from the old Polymer80 brand, which stopped making frames in 2024; we are not affiliated with it or with Glock.

The law: the frame is the firearm

Under federal law the frame or receiver is the regulated part of a pistol. Since the ATF's 2022 rule, which the US Supreme Court upheld in 2025, that also includes frame and receiver kits that can readily be completed. That means every frame must carry a serial number, and you buy it from a licensed dealer with a Form 4473 and a background check, the same as a complete pistol. You must be 21 to buy a handgun frame from a dealer. Everything we sell as a frame is serialized and ships to your dealer. Some states go further and ban or restrict unserialized or home-built guns; Arizona does not add its own rules, but check yours if you live elsewhere.

Parts that ship to your door

Slides: complete or stripped, with optic cuts, windows and serrations. Match the slide to the frame generation and size.
Barrels: stainless or nitrided, threaded or flush. Match barrel length to slide length.
Triggers: flat-face and curved shoes, drop-in kits and connectors. Keep your trigger safe and drop safety functional.
Sights and optics: suppressor-height irons, fiber optics and red dots with the right footprint for your slide cut.
Magazines: factory and aftermarket magazines in the capacities legal where you live.

Compatibility

Glock-pattern parts are divided by size and generation. Gen 3 parts are the most widely supported; Gen 5 slides and frames differ in several internal parts. Compact (19-size), full-size (17-size) and subcompact (26 and 43-size) parts do not mix. Check the maker's compatibility chart before you order.

Testing a finished pistol

Function-check the trigger reset, safeties and slide lock with an empty gun.
Fire your first rounds one at a time, then fill the magazine.
Shoot several hundred rounds of your practice and defensive ammunition before you carry it.
Keep the original parts and receipts in case you need warranty help.

What we never sell

We do not sell unserialized frames, jigs for completing them, or any part that makes a firearm fire more than one shot per trigger pull. Those items are illegal or tightly regulated, and they are blocked from our catalog.

Where to test

Arizona Game and Fish Department ranges such as Ben Avery in Phoenix, Three Points near Tucson and the Northern Arizona range near Flagstaff are good places to break in a build.

Shop frames and receivers, complete pistols and slides, and read the Arizona gun law guide.

General information, not legal advice. Current as of September 2026. Laws change; check the official source before you act.