What This Bill Does · Plain English
Summary · Congress.gov
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.
Action Timeline
2025-06-27
Introduced in House
2025-06-27
Referred to the House Committee on the Judiciary.
2025-06-27
Introduced in House
Frequently Asked Questions
Did HR.4221 pass?
HR.4221 is still alive. Current stage: COMMITTEE. Pass likelihood: pending.
What does HR.4221 do?
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 th…
Who sponsored HR.4221?
HR.4221 was sponsored by Madeleine Dean (D-Pennsylvania).
Full Bill Text
119 HR 4221 IH: Undetectable Firearms Modernization Act U.S. House of Representatives 2025-06-27 text/xml EN Pursuant to Title 17 Section 105 of the United States Code, this file is not subject to copyright protection and is in the public domain. I 119th CONGRESS 1st Session H. R. 4221 IN THE HOUSE OF REPRESENTATIVES June 27, 2025 Ms. Dean of Pennsylvania introduced the following bill; which was referred to the Committee on the Judiciary A BILL To modernize the Undetectable Firearms Act of 1988. 1. Short title This Act may be cited as the Undetectable Firearms Modernization Act . 2. Modernization of the prohibition on undetectable firearms Section 922(p) of title 18, United States Code, is amended— (1) in paragraph (1)— (A) in subparagraph (A), by striking grips, stocks, and magazines, is not as detectable as the Security Exemplar, by walk-through metal detectors calibrated and operated to detect the Security Exemplar and inserting all parts other than major components, does not contain detectable material ; and (B) in subparagraph (B), by striking when subjected to inspection by the types of x-ray machines commonly used at airports, does not generate and inserting the following: if subjected to inspection by the types of detection devices commonly used at airports for security screening, would not generate ; (2) in paragraph (2)— (A) by striking subparagraph (B) and inserting the following: (B) the term major component , with respect to a firearm— (i) means the slide or cylinder, or the frame or receiver of the firearm; and (ii) in the case of a rifle or shotgun, includes the barrel of the firearm; and ; and (B) by striking subparagraph (C) and the proviso that follows and inserting the following: (C) the term detectable material means material that produces a magnetic field that is equivalent in strength to the magnetic field produced by 3.7 ounces of 17–4 PH stainless steel. ; (3) in paragraph (3)— (A) in the first sentence, by inserting after of a firearm the following: , including a prototype, ; and (B) by striking the second sentence; and (4) in paragraph (5), by striking shall not apply to any firearm which and all that follows and inserting the following: shall not apply to— (A) any firearm received by, in the possession of, or under the control of the United States; or (B) the manufacture, importation, possession, transfer, receipt, shipment, or delivery of a firearm by a licensed manufacturer or licensed importer pursuant to an existing contract with the United States. .
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