ATF Final Rule 2021R-08F, the 2023 stabilizing brace rule, is not in effect and imposes no obligations on firearm owners. A federal district court vacated it nationwide on June 13, 2024, and in May 2026 the ATF proposed formally removing its text from the Code of Federal Regulations.1Federal Register. Removing Factoring Criteria for Firearms With Attached Stabilizing Braces If you own a pistol with a stabilizing brace, you are not required to register it, remove the brace, or take any action under this rule. Two situations still deserve attention: owners who registered during the 2023 forbearance window and did not withdraw the application, and the general concept of constructive possession, which the vacatur does not touch.
What the Rule Tried to Do
Published in the Federal Register on January 31, 2023, with an effective date of June 1, 2023, Rule 2021R-08F amended the regulatory definitions in 27 CFR 478.11 and 27 CFR 479.11. It introduced a point-based evaluation, sometimes called ATF Worksheet 4999, to decide whether a braced pistol was “designed and intended to be fired from the shoulder.” A firearm scoring four or more points on either the accessory characteristics section or the weapon configuration section would be classified as a rifle. Because a rifle with a barrel under 16 inches is a short-barreled rifle under the National Firearms Act, that reclassification pulled the firearm into a heavily regulated category.2Office of the Law Revision Counsel. 26 USC 5845 – Definitions
The worksheet only applied to firearms within certain physical parameters. Weapons under 64 ounces (4 pounds) without a magazine were excluded as too light to need a stabilizing brace. Firearms shorter than 12 inches overall or longer than 26 inches overall were also excluded. Within those bounds, the worksheet scored features like brace adjustability, rear surface area, how much the brace wrapped the forearm, and the length of pull measured from the trigger to the rear center of the brace. A length of pull of 13.5 inches or more alone scored four points and classified the weapon as a rifle.3Federal Register. Factoring Criteria for Firearms With Attached Stabilizing Braces
Owners of firearms that would score as rifles had a 120-day forbearance window beginning January 31, 2023. During that window, they could register the firearm as an SBR without paying the standard $200 making tax, replace the barrel with one 16 inches or longer, permanently remove the brace, turn the firearm in to a local ATF field office, or destroy it.
How the Courts Killed It
Legal challenges came almost immediately. The most consequential was Mock v. Garland in the Northern District of Texas. On appeal, the Fifth Circuit reversed the district court’s initial denial of a preliminary injunction, finding that the plaintiffs were likely to succeed on administrative law grounds.4Justia. Mock v. Garland, No. 23-10319 (5th Cir. 2023) On November 8, 2023, a district court in the Northern District of Texas stayed the entire rule nationwide. On June 13, 2024, the same court granted summary judgment for the plaintiffs and vacated the rule universally, finding it violated the Administrative Procedure Act.
The ATF has stated that “for all intents and purposes” it never actively enforced the 2023 final rule because of the litigation and court orders.1Federal Register. Removing Factoring Criteria for Firearms With Attached Stabilizing Braces The May 2026 proposed rulemaking would strike the 2021R-08F text from the CFR entirely, so the regulatory language disappears rather than sitting on the books blocked by a court order. Without that framework, the ATF reverts to its pre-2023 approach of case-by-case classification through individual determination letters.
The Underlying Law Is Unchanged
The vacatur removed the ATF’s specific test for when a brace turns a pistol into a rifle. It did not change the statutes underneath. The National Firearms Act still defines a short-barreled rifle as a rifle with a barrel under 16 inches, and the Gun Control Act still defines a rifle as a weapon designed, made, and intended to be fired from the shoulder.5Office of the Law Revision Counsel. 18 USC 921 – Definitions Making or possessing an unregistered NFA firearm remains a federal crime carrying a fine of up to $10,000, imprisonment for up to 10 years, or both.6Office of the Law Revision Counsel. 26 USC 5871 – Penalties
What that means in practice: a braced pistol as normally configured and used is not currently treated as an SBR. But if a firearm is objectively built and used as a shoulder-fired weapon with a short barrel, the underlying statutes still reach it, worksheet or no worksheet.
If You Registered During the Forbearance Window
Thousands of owners filed ATF Form 1 during the 2023 forbearance period. After the vacatur, those applications sat unresolved for over a year. The ATF eventually set a deadline: applicants could withdraw the application by November 10, 2025, or the ATF would process it. Owners who took no action had their registrations processed beginning November 11, 2025.7Bureau of Alcohol, Tobacco, Firearms and Explosives. Information Regarding Pending NFA Forbearance Applicants Submitted Pursuant to the Vacated Final Rule 2021R-08F Pertaining to Stabilizing Braces
If your registration went through, the firearm is now on the National Firearms Registration and Transfer Record. That comes with real obligations that ordinary pistol owners do not have. You need prior written ATF authorization on Form 5320.20 before transporting the firearm across state lines, and that approval covers only a specific time period, so a new form is required for each trip.8Bureau of Alcohol, Tobacco, Firearms and Explosives. Application to Transport Interstate or to Temporarily Export Certain National Firearms Act (NFA) Firearms Anyone other than a licensed dealer, manufacturer, or importer who moves an SBR across state lines without authorization violates federal law.9Office of the Law Revision Counsel. 18 USC 922 – Unlawful Acts You must keep the approved Form 1 accessible, and any future transfer has to go through an NFA dealer with the appropriate tax and paperwork.
Owners who withdrew the application by the deadline are in the same legal position as everyone else with a braced pistol: no registration, no rule, no obligation.
Constructive Possession Still Applies
The vacatur does not eliminate the doctrine of constructive possession. Federal prosecutors can bring charges for possession of an unregistered NFA firearm based not on a fully assembled weapon but on having the parts together with apparent intent to build one. Courts look at whether the person owns most of the components needed, whether those parts have any lawful use outside an NFA configuration, and whether the circumstances suggest intent to assemble them.
Storing a short barrel next to a pistol receiver with a bare buffer tube, or buying SBR components in quick succession, can create legal exposure even if nothing is actually assembled. The safest approach is to avoid keeping parts together that have no purpose outside a restricted configuration unless the firearm itself is registered.
State Law Boundary
Federal vacatur does not override state law. Several states restrict short-barreled rifles independently, and some prohibit them regardless of federal registration status. If you registered a braced pistol as an SBR during the forbearance window, check whether your state treats a federally registered SBR differently from an unregistered one before assuming registration alone made possession lawful where you live. For everyone else, state rules on braces and pistol configuration operate on their own terms and are not affected by the fate of Rule 2021R-08F.