The ATF Frame or Receiver Rule and 80% Kits, Explained

Last updated 24 October 2026. This is general information, not legal advice. Laws change and states differ, so confirm the current rule before you buy or build.

The short answer

The ATF "frame or receiver" rule took effect on 24 August 2022 (ATF letter). It treats weapon parts kits and partially complete frames or receivers that can readily be converted to fire as firearms. On 26 March 2025 the Supreme Court held 7 to 2 that the rule is not facially inconsistent with the Gun Control Act (Faegre Drinker summary). Litigation did not stop there.

What the Supreme Court did and did not decide

It decided a facial challenge only: the rule's definitions can be applied validly to at least some items.
It gave no opinion on whether the rule is valid as applied to a specific product. The Congressional Research Service has a longer legal summary.
Justices Thomas and Alito dissented.

What happened after

A September 2026 commentary from the Independent Institute reports that on 17 August 2026 a federal judge in the Northern District of Texas, in Defense Distributed v. Blanche, declared the rules unconstitutionally vague and in violation of the Second Amendment. We have not confirmed whether that ruling is in force or under appeal. Treat the federal rule as contested and check current news.

What this means for a buyer

Products sold as unfinished frames, receivers or kits may be treated as firearms, with serial numbers, dealer transfers and background checks, depending on the product and the rule in force.
Many states set their own rules on unfinished frames and receivers, and some ban them. Check your state before ordering.
Ask the seller how the item is classified. If a seller will not say, do not buy.

Background on the company

Polymer80, the best known maker of these kits, stopped operating in 2024. See what happened to Polymer80.

Sources

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