Short-Barreled Rifles (SBRs): Rules, Building, and Transport
A short-barreled rifle (SBR) is a rifle with a barrel under 16 inches, or an overall length under 26 inches. Because it falls under the National Firearms Act, an SBR is regulated more heavily than a standard rifle and requires ATF registration and a $200 tax stamp.
SBRs are popular because a shorter barrel makes a rifle more compact and maneuverable while keeping rifle-caliber performance. This guide covers how the ATF defines an SBR, the two ways to get one, and the transport rules that trip up new owners.
This is general information, not legal advice; verify with the ATF or a qualified attorney.
What makes a rifle an SBR
A firearm is an SBR under the NFA if it is a rifle (designed to be fired from the shoulder) with a rifled barrel shorter than 16 inches, or with an overall length under 26 inches. Measurement matters: barrel length is measured with the action closed, and a permanently attached muzzle device can count toward the 16-inch minimum if it is pinned and welded.
A pistol built on an AR-style receiver with a brace is a separate legal category and is not automatically an SBR, but configuration details matter a great deal here — get specifics right before you build.
Two ways to get an SBR: buy or build
You can buy a factory SBR from a dealer using an ATF Form 4, just like a suppressor, paying the $200 transfer tax and waiting for approval. Alternatively, you can make your own SBR from a rifle or receiver you already own by filing an ATF Form 1 (Application to Make and Register a Firearm) and paying the $200 making tax before you assemble it.
The key rule for building: approval must come first. You cannot assemble the short-barreled configuration until your Form 1 is approved.
- Buy a factory SBR: ATF Form 4, $200 transfer tax
- Build your own: ATF Form 1, $200 making tax, approval before assembly
- Fingerprints, photo, and CLEO notification apply either way
Engraving requirements for Form 1 makers
If you build an SBR on a Form 1, you become the maker and must engrave the firearm with your name (or trust name) and city and state, along with any other markings the ATF requires. The engraving must meet minimum depth and character-height standards.
Many makers have a local engraver or their dealer handle this to ensure it meets ATF specifications. Buying a factory SBR on a Form 4 avoids this step because the manufacturer already marked it.
Interstate transport and Form 5320.20
Unlike suppressors, an SBR requires ATF permission before you permanently move it to another state or take it across state lines temporarily. You request this approval by filing ATF Form 5320.20. The form is free and can be filed through eForms.
Plan ahead if you are traveling to a match, a hunt, or a move: get the 5320.20 approved before you cross the state line with the SBR.
State-law variance
Several states ban SBRs for civilians even with a federal tax stamp, and a few restrict specific configurations under their assault-weapon statutes. Confirm both that your state allows SBRs and that your specific build is not separately prohibited.
Our state-by-state NFA reference tracks SBR legality across all 50 states.
Frequently asked questions
Is a pistol brace the same as an SBR?
No. A pistol with a stabilizing brace is legally distinct from an SBR, though the rules around braces have been contentious and configuration details matter. If you attach a true shoulder stock and a barrel under 16 inches, you have made an SBR and need a tax stamp first.
Can I put a stock on my AR pistol without registering?
Adding a shoulder stock to a firearm with a sub-16-inch barrel generally creates an SBR, which requires an approved Form 1 and a $200 tax stamp before assembly. Do not assemble the configuration until you have approval.
Do I need ATF permission to drive my SBR to another state?
Yes. SBRs, SBSs, and machine guns require an approved ATF Form 5320.20 before crossing state lines. The form is free and can be filed electronically. Suppressors and AOWs do not require this.
How long does an SBR tax stamp take now?
With the ATF's improved eForms system, electronically filed Form 1 and Form 4 applications for individuals and trusts often clear in days to weeks, a major improvement over the old multi-month waits.
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Last reviewed 2026-07-07.