# 119-hr-4221: Undetectable Firearms Modernization Act

119-hr-4221, Undetectable Firearms Modernization Act, is a 119th Congress bill sponsored by Rep. Dean, Madeleine [D-PA-4] (D-PA); status introduced (as of 2026-04-21).

- Canonical: https://policyrisk.com/legislation/119-hr-4221
- As of: 2026-04-21
- Plain-text twin of the page above; the HTML and this file carry the same facts.

## Facts
- Bill: 119-hr-4221
- Congress: 119
- Title: Undetectable Firearms Modernization Act
- Status: introduced
- Introduced: 2025-06-27
- Sponsor: Rep. Dean, Madeleine [D-PA-4] (D-PA)
- Cosponsors: 0
- Policy area: Crime and Law Enforcement
- Touches household money: no
- Last recorded action: 2026-04-21

## Summary

**Modernizes the definition of undetectable firearms.** This bill would update how parts and materials are judged detectable, align the test with modern airport security screening devices, and bring prototypes explicitly into scope.

## Provisions PRIA read

- Stronger rules to spot undetectable guns: benefit, medium. This bill would update how undetectable guns are tested. Airport security screening devices would be the standard, not older X-ray rules. A gun would count as undetectable only if non‑major parts have no detectable material. Detectable material would mean a magnetic field like 3.7 ounces of 17-4 PH…
- Federal and contractor waivers on undetectable guns: benefit, low. This bill would keep the ban from applying when a firearm is received by or under U.S. control. Licensed manufacturers or importers would also be exempt when working under an existing U.S. contract. These exemptions would apply only in those cases.
- Prototype gun makers face same limits: cost, low. This bill would clearly cover prototype or experimental guns. Makers and hobbyists would face the same limits and penalties as for other firearms. If you build prototypes, you would need to follow the undetectable‑firearm rules.

## Related bills

- 119-hr-7977: Energy Bills Relief Act
- 119-hr-7481: Department of Homeland Security Appropriations Act, 2026
- 119-hr-7973: Momnibus Act
- 119-hr-5658: Child Care for Every Community Act
- 119-hr-3971: Domestic Workers Bill of Rights Act
- 119-hr-2913: Ukraine Support Act

## Sources
- [119-hr-4221 on Congress.gov](https://www.congress.gov/bill/119th-congress/house-bill/4221)

## Related
- [119-hr-7977: Energy Bills Relief Act](https://policyrisk.com/legislation/119-hr-7977)
- [119-hr-7481: Department of Homeland Security Appropriations Act, 2026](https://policyrisk.com/legislation/119-hr-7481)
- [119-hr-7973: Momnibus Act](https://policyrisk.com/legislation/119-hr-7973)
- [119-hr-5658: Child Care for Every Community Act](https://policyrisk.com/legislation/119-hr-5658)
- [119-hr-3971: Domestic Workers Bill of Rights Act](https://policyrisk.com/legislation/119-hr-3971)
- [119-hr-2913: Ukraine Support Act](https://policyrisk.com/legislation/119-hr-2913)
- [All bills in Congress](https://policyrisk.com/legislation)

Source: PRIA, https://policyrisk.com/legislation/119-hr-4221 (as of 2026-04-21).