H.R.4221 'Undetectable Firearms Modernization Act' would update federal standards for undetectable firearms; referred to House Judiciary
Federal bill HR 4221 — status: in committee
Official title: Undetectable Firearms Modernization Act
What it does
H.R.4221, titled the Undetectable Firearms Modernization Act, would amend the federal Undetectable Firearms Act to update definitions and detection standards for firearms to account for modern manufacturing methods. The measure was introduced in the House and on June 27, 2025 was referred to the House Committee on the Judiciary. Interested parties should consult the bill text for exact statutory language and definitions proposed.
Industry impact
If enacted, the bill would primarily affect makers and assemblers of non-traditional firearms (for example, those using polymer frames or additive manufacturing) by changing what constitutes an unlawful 'undetectable' firearm. Manufacturers and some FFLs may need to adjust product designs, add detectable components or markings, or change compliance screening procedures to avoid prohibited configurations. Retailers and NFA/SOT holders could see limited downstream effects in the form of new compliance checks or clearer restrictions on transfers of items that fall within the updated definition.
Latest official status: Referred to the House Committee on the Judiciary.
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