Short-Barreled Shotguns (SBSs): NFA Rules and How to Own One

A short-barreled shotgun (SBS) is a shotgun with a barrel shorter than 18 inches, or an overall length under 26 inches. Like short-barreled rifles, SBSs are regulated under the National Firearms Act and require ATF registration and a $200 tax stamp.

SBSs are prized for home defense and close-quarters use because a shorter barrel is more maneuverable. This guide explains the legal definition, the buy-versus-build paths, and the rules unique to shotguns.

This is general information, not legal advice; verify with the ATF or a qualified attorney.

What makes a shotgun an SBS

Under the NFA, a shotgun is an SBS if it has a smooth-bore barrel under 18 inches (note the 18-inch minimum, not 16 as with rifles) or an overall length under 26 inches. The measurement is taken with the action closed.

Be careful with firearms like the Mossberg Shockwave or Remington TAC-14: these ship with a bird's-head grip and are technically classified as 'firearms' rather than shotguns, so they are not SBSs. Adding a traditional stock to one, however, can create a regulated SBS.

Buying vs. building an SBS

You can buy a factory SBS from a dealer on an ATF Form 4 with a $200 transfer tax, or make one from a shotgun you already own by filing an ATF Form 1 with a $200 making tax. As with SBRs, you must have Form 1 approval in hand before you shorten a barrel or assemble the configuration.

Both paths require fingerprints, a photo, and CLEO notification under the 41F rule.

Buy a factory SBS: Form 4, $200 transfer tax
Build your own: Form 1, $200 making tax, approval before you cut or assemble
18-inch barrel minimum (vs. 16 inches for rifles)

Engraving requirements for makers

If you make an SBS on a Form 1, you must engrave your name (or trust name) and city and state on the firearm, meeting the ATF's minimum depth and character-size standards. A factory SBS bought on a Form 4 is already marked by the manufacturer, so no additional engraving is needed.

Interstate transport

SBSs are subject to the same interstate transport rules as SBRs and machine guns: you need an approved ATF Form 5320.20 before taking the SBS across state lines. The form is free and filed through eForms. Suppressors and AOWs are exempt from this requirement.

State-law variance

Some states ban SBSs entirely for civilians, even with a federal tax stamp, and others fold them into broader restricted-weapon categories. Always confirm your state's rules before starting the process. Our state NFA reference tracks SBS legality nationwide.

Frequently asked questions

Is a Mossberg Shockwave an SBS?

No. Firearms like the Shockwave and TAC-14 ship with a bird's-head grip and are legally classified as non-NFA 'firearms,' not shotguns. Adding a shoulder stock can turn one into a regulated SBS requiring a tax stamp, so do not modify it without understanding the reclassification.

What is the minimum barrel length before a shotgun becomes an SBS?

A shotgun barrel must be at least 18 inches, and the overall length at least 26 inches, to stay out of NFA regulation. Below either threshold, it is an SBS requiring registration and a $200 tax stamp.

Can I build an SBS from my hunting shotgun?

Yes, if it is legal in your state. File an ATF Form 1, pay the $200 making tax, and wait for approval before cutting the barrel or otherwise creating the short-barreled configuration. You must also engrave the firearm as the maker.

Do SBSs need transport approval like SBRs?

Yes. SBSs require an approved ATF Form 5320.20 before crossing state lines, the same as SBRs and machine guns. The form is free to file electronically.

Last reviewed 2026-07-07.