Short shotguns are legal to own in the United States, and there are two routes: buy a factory-built pistol-grip firearm like the Mossberg Shockwave through an ordinary dealer transaction with no federal registration, or register a true short-barreled shotgun with the ATF. Which route a given firearm falls into depends on two measurements and one design question. Get those wrong and a legal purchase becomes a federal felony.
The Measurements That Decide Everything
Federal law draws its lines at 18 inches of barrel length and 26 inches of overall length. Under the National Firearms Act, a shotgun with a barrel shorter than 18 inches is an NFA “firearm” that must be registered. The same applies to any weapon made from a shotgun if the modified version has a barrel under 18 inches or an overall length under 26 inches.1ATF. Chapter 2 – What Are Firearms Under the NFA Meet both minimums and the gun is regulated like any other long gun.
The definition of “shotgun” carries as much weight as the numbers. Federal law defines a shotgun as a weapon designed to be fired from the shoulder that uses a fixed shotgun shell fired through a smooth bore.2Office of the Law Revision Counsel. 26 U.S. Code 5845 – Definitions The phrase “designed to be fired from the shoulder” is what opens the door to a whole category of short firearms that avoid NFA regulation entirely.
Non-NFA Pistol-Grip Firearms
The most popular short shotguns on the market are firearms like the Mossberg Shockwave. They ship from the factory with a pistol grip instead of a shoulder stock, a barrel around 14 inches, and an overall length just over 26 inches (typically 26.37 inches). Because they were never designed to fire from the shoulder, the ATF has determined they do not meet the federal definition of a shotgun. And because they exceed 26 inches overall, they are too large to qualify as a concealable “any other weapon.” They fall into the Gun Control Act’s generic “firearm” category and avoid NFA regulation entirely.1ATF. Chapter 2 – What Are Firearms Under the NFA
Buying one works like buying any regular gun. You go through a Federal Firearms Licensee, fill out an ATF Form 4473, and pass a NICS background check.3Federal Bureau of Investigation. Firearms Checks (NICS) No registration. No ATF application. No wait beyond the background check.
There is a catch on the purchase side. Because these firearms are not legally rifles or shotguns, they do not qualify for the interstate sale exception that lets you buy a long gun from a dealer in another state. An FFL can only sell a non-rifle, non-shotgun firearm to a resident of the same state. If you want one from an out-of-state dealer, it has to ship to a licensed dealer in your home state for transfer there.4Bureau of Alcohol, Tobacco, Firearms and Explosives. Federal Firearms Licensee Quick Reference and Best Practices Guide
The same classification issue affects age. Federal law prohibits licensed dealers from selling any firearm other than a rifle or shotgun to anyone under 21. Since these pistol-grip guns are legally neither, most FFLs require buyers to be at least 21.
Registered Short-Barreled Shotguns and AOWs
If a shotgun has a barrel under 18 inches or an overall length under 26 inches and it was designed with a shoulder stock, it is a short-barreled shotgun under the NFA. The same classification applies to any standard shotgun cut down below those thresholds.2Office of the Law Revision Counsel. 26 U.S. Code 5845 – Definitions Owning one is legal at the federal level, but only if it is registered in the National Firearms Registration and Transfer Record. Possessing an unregistered SBS is a federal felony.5Office of the Law Revision Counsel. 26 USC Chapter 53 – Machine Guns, Destructive Devices, and Certain Other Firearms
A separate NFA category called “any other weapon” (AOW) covers some short, concealable shotgun-type firearms, including smooth-bore pistols designed to fire shotgun shells and certain combination-barrel weapons shorter than 18 inches.6eRegulations ATF eRegulations. 27 CFR Part 479 Commerce in Firearms and Ammunition AOWs follow the same NFA registration process.
The 2025 $0 Tax Stamp Change
Many sources online still show the old $200 tax. In 2025, Public Law 119-21 amended the NFA’s tax provisions. Previously, transferring or making an SBS, AOW, suppressor, or short-barreled rifle cost $200 in tax (with a $5 exception for AOW transfers). The new law sets the tax at $0 for every NFA firearm except machineguns and destructive devices.5Office of the Law Revision Counsel. 26 USC Chapter 53 – Machine Guns, Destructive Devices, and Certain Other Firearms
The updated ATF forms reflect this. Form 4, used for transfers, now states that the transfer tax is $0 for NFA firearms other than machineguns and destructive devices.7Bureau of Alcohol, Tobacco, Firearms, and Explosives. Application to Transfer and Register NFA Firearm (Tax-Paid) – ATF Form 5320.4 (Form 4) Form 1, used when making a new NFA firearm, says the same about the making tax.8Bureau of Alcohol, Tobacco, Firearms, and Explosives. Application to Make and Register NFA Firearm (ATF Form 5320.1)
The tax is gone. Every other requirement remains. You still submit an ATF application, pass a background check, provide fingerprints and photographs, and wait for approval.
How to Register
Two paths, depending on whether you are buying an existing NFA firearm or building your own.
Buying From a Dealer
To buy an existing NFA firearm, you submit ATF Form 4. The application requires your personal information, a description of the firearm, a 2×2-inch photograph taken within six months, and fingerprints on FBI Form FD-258.7Bureau of Alcohol, Tobacco, Firearms, and Explosives. Application to Transfer and Register NFA Firearm (Tax-Paid) – ATF Form 5320.4 (Form 4) As of January 2026, electronic Form 4 applications were averaging about 10 to 11 days for approval.9ATF. Current Processing Times Paper submissions take significantly longer. You cannot take possession until the ATF approves the transfer.10Office of the Law Revision Counsel. 26 U.S. Code 5812 – Transfers
Making Your Own
To build a short-barreled shotgun yourself, such as by cutting down an existing shotgun barrel, file ATF Form 1 before doing any work. The same fingerprint and photo requirements apply.8Bureau of Alcohol, Tobacco, Firearms, and Explosives. Application to Make and Register NFA Firearm (ATF Form 5320.1) Electronic Form 1 applications averaged about 14 days in January 2026.9ATF. Current Processing Times Wait for approval before starting any modification. Cutting first and paperwork later is a federal crime, regardless of intent to register.
Using an NFA Trust
Instead of registering as an individual, many owners use a gun trust. Co-trustees named in the trust can legally possess and transport the registered firearm without their own separate registration. For an individually registered NFA item, only the registered owner can lawfully possess it. A trust solves that for households, shooting partners, or anyone who wants shared legal access. Each co-trustee listed on the trust at the time of application must submit fingerprints and photographs.
Modifications That Turn a Legal Gun Into a Felony
This is where owners get into trouble. Adding a shoulder stock to a non-NFA firearm like the Shockwave turns it into a short-barreled shotgun the moment the stock goes on. The gun becomes “designed to be fired from the shoulder” with a barrel under 18 inches, matching the NFA definition exactly.2Office of the Law Revision Counsel. 26 U.S. Code 5845 – Definitions Without a previously approved Form 1, installing that stock is a federal felony carrying up to 10 years in prison.11Office of the Law Revision Counsel. 26 U.S. Code 5871 – Penalties
Federal courts also recognize constructive possession. If you own all the parts needed to assemble an unregistered NFA firearm and those parts have no other lawful configuration, prosecutors can argue you already possess an illegal weapon, even if you never actually assembled anything. Owning a pistol-grip shotgun alongside a short barrel and a detached shoulder stock could support that argument. The safe approach is to avoid holding a parts combination that could only produce an NFA weapon unless you have an approved Form 1 for that configuration.
Crossing State Lines
Interstate travel rules depend on which type you own.
Non-NFA firearms like the Shockwave need no ATF notification to cross state lines. Transport them like any other firearm, subject to the laws of each state you enter. The federal safe passage provision under 18 U.S.C. ยง 926A protects you while traveling through a state with restrictive laws, provided the firearm is unloaded and stored where it is not readily accessible from the passenger compartment. A locked trunk works; if the vehicle has no trunk, use a locked container.12Office of the Law Revision Counsel. 18 U.S. Code 926A – Interstate Transportation of Firearms That protection covers passing through. Stop for an extended period and local law applies.
Registered short-barreled shotguns are treated differently. Federal law prohibits anyone other than a licensed dealer, manufacturer, or importer from transporting an SBS across state lines without prior written authorization from the ATF. You submit ATF Form 5320.20 and wait for approval before traveling.13Bureau of Alcohol, Tobacco, Firearms and Explosives. Application to Transport Interstate or to Temporarily Export Certain National Firearms Act (NFA) Firearms (ATF Form 5320.20) The requirement applies to short-barreled shotguns, short-barreled rifles, machineguns, and destructive devices.14Office of the Law Revision Counsel. 18 USC 922 – Unlawful Acts Registered AOWs are not on that list, so they do not require Form 5320.20 for interstate transport.
Penalties for Getting It Wrong
Possessing an unregistered short-barreled shotgun, failing to register a firearm you have modified, or any other NFA violation carries a maximum penalty of 10 years in federal prison and a $10,000 fine.11Office of the Law Revision Counsel. 26 U.S. Code 5871 – Penalties Any firearm involved in a knowing violation is also subject to seizure and forfeiture.15eRegulations – ATF eRegulations. 27 CFR 478.152 Seizure and Forfeiture “I didn’t know” is not a defense that typically succeeds.
State and Local Law Can Override
Federal legality does not guarantee you can own or carry a short shotgun where you live. Some states ban short-barreled shotguns outright, even registered NFA items. Others prohibit non-NFA firearms like the Shockwave by classifying them differently under state law. A handful impose their own registration or permit requirements on top of federal rules. Check your state’s statutes and any local ordinances before purchasing. Federal compliance is necessary, but not always sufficient.