Factoring Criteria for Firearms with Attached “Stabilizing Braces”

Three stabilizing races attached to machine guns laying on a table

On January 13, 2023, the Attorney General signed ATF final rule 2021R-08F, “Factoring Criteria for Firearms with Attached ‘Stabilizing Braces,’” amending ATF’s regulations to clarify when a rifle is designed, made, and intended to be fired from the shoulder. The final rule was published in the Federal Register on January 31, 2023. 

The rule outlines the factors ATF would consider when evaluating firearms equipped with a purported “stabilizing brace” (or other rearward attachment) to determine whether these weapons would be considered a “rifle” or “short-barreled rifle” under the Gun Control Act of 1968, or a “rifle” or “firearm” subject to regulation under the National Firearms Act. The rule’s amended definition of “rifle” clarifies that the term “designed, redesigned, made or remade, and intended to be fired from the shoulder” includes a weapon that is equipped with an accessory, component, or other rearward attachment (e.g., a “stabilizing brace”) that provides surface area that allows the weapon to be fired from the shoulder, provided other factors, as listed in the definition, indicate the weapon is designed and intended to be fired from the shoulder.

This rule does not affect “stabilizing braces” that are objectively designed and intended as a “stabilizing brace” for use by individuals with disabilities, and not for shouldering the weapon as a rifle. Such stabilizing braces are designed to conform to the arm and not as a buttstock. This rule is effective on January 31, 2023, the date it was published in the Federal Register.  If the firearm with the “stabilizing brace” is a short-barreled rifle, affected person have 120 days from the date of publication to register the firearm tax-free, which is May 31, 2023.

Other compliance options provided under the final rule are the following:

  • Remove the short barrel and attach a 16-inch or longer rifled barrel to the firearm,
  • Permanently remove and dispose of, or alter, the “stabilizing brace” such that it cannot be
  • reattached,
  • Turn the firearm into your local ATF office,
  • Destroy the firearm,

The option to register the firearm tax-free pursuant to ATF Final Rule 2021R-08F is scheduled to be discontinued in the eForms System effective May 31, 2023 at 11:59 p.m. (ET).



Who is Affected by this Rule?

  • Unlicensed Possessors
  • Federal Firearms Licensees (FFLs) not under the NFA as a Class One Importer or Class Two Manufacturer SOT
  • FFL Importers or Manufacturers under the GCA that ARE Qualified under the NFA Class One Importer or Class Two Manufacturer SOT
  • Certain Governmental Entities

What Do You Need to Know?

Affected parties are provided a range of options to remain in compliance with rule 2021R-08F. ATF has provided this quick reference sheet to provide these options.  For questions not answered by the reference sheet, we have provided a comprehensive list of FAQs.

Related Resources

Related Research and Background Information

Contact Information

  • For questions regarding the application of the final rule, contact the Firearms Industry Programs Branch at Firearms Industry Programs Branch: FIPB@atf.gov.
  • For technical questions regarding firearms, contact the Firearms and Ammunition Technology Division at: Fire_Tech@atf.gov.
  • For questions regarding the rulemaking process, contact the Office of Regulatory Affairs at ORA@atf.gov.
  • To register for an eForms account and/or submit an eForm 1 pursuant to ATF Final Rule 2021R-08F, please visit https://eforms.atf.gov/login
Last Reviewed May 25, 2023