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H.R. 4221 119th Congress House

Undetectable Firearms Modernization Act

Official title: To modernize the Undetectable Firearms Act of 1988.

Introduced: June 27, 2025 Introduced by: Madeleine Dean Democratic · Pennsylvania See on congress.gov
Crime and Law Enforcement
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 Everywhere this bill has been 2 steps
Introduced
In committee
Reported out
Passed House
Passed Senate
To President
Became law
Jun 27, 2025
Referred to the House Committee on the Judiciary.
Jun 27, 2025
Introduced in House
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What's happening now June 27, 2025

Referred to the House Committee on the Judiciary.

 Plain-English summary Congressional Research Service

Undetectable Firearms Modernization Act

This bill strengthens the detectability standard for firearms under federal firearms laws.  

Current law requires firearms to be detectable by walk-through metal detectors after the removal of grips, stocks, and magazines. Specifically, firearms must be as detectable as a security exemplar (i.e., a piece of stainless steel that is 3.7 ounces and in a shape resembling a handgun). There are exceptions, including for firearms manufactured for or sold to U.S. military or intelligence agencies.

This bill requires firearms to contain detectable material after the removal of all parts other than major components. It defines detectable material as material that produces a magnetic field equivalent to that produced by 3.7 ounces of stainless steel. The bill also revises and broadens the exceptions to include firearms (1) received by, in the possession of, or under the control of the United States; or (2) produced pursuant to a contract with the United States.

 Bill text 1 version

Source documents hosted by congress.gov.

 Committees of jurisdiction 1
 Lobbying activity 6

Registered lobbyists who named this bill in their disclosure filings. Source: federal Lobbying Disclosure Act filings.

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Cite this page click to expand
APA
U.S. Congress. (2026). H.R. 4221: Undetectable Firearms Modernization Act. 119th Congress. Open America. https://openamerica.io/bill/119-HR-4221/
MLA
"H.R. 4221: Undetectable Firearms Modernization Act." 119th Congress, 2026, Open America, https://openamerica.io/bill/119-HR-4221/.
Bluebook (legal)
H.R. 4221, 119th Cong. (2026), https://openamerica.io/bill/119-HR-4221/.
Markdown link
[H.R. 4221: Undetectable Firearms Modernization Act](https://openamerica.io/bill/119-HR-4221/)
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