Yes, 40mm launchers are legal for civilians to own in most of the United States, but almost every 40mm launcher is a “destructive device” under the National Firearms Act, which means you register it with the ATF, pay a $200 tax, pass a background check, and confirm your state allows it before you take possession. A handful of states ban destructive devices outright, and holding an unregistered one is a federal felony carrying up to ten years in prison.1Office of the Law Revision Counsel. 26 USC 5871 – Penalties
Why a 40mm Launcher Is a Destructive Device
The NFA defines a destructive device two ways that matter here. It covers explosive ordnance carrying more than a quarter ounce of explosive charge, and it covers any weapon with a barrel bore larger than half an inch. A standard 40mm launcher has a bore of roughly 1.57 inches, which puts it in the second category no matter what round you plan to fire.2Office of the Law Revision Counsel. 26 USC 5845 – Definitions
The statute contains a narrow exemption for devices that were never designed as weapons, or that were redesigned solely for signaling, pyrotechnic, line-throwing, or safety use. That exemption keeps dedicated flare launchers off the registry. It does not help a 40mm grenade launcher such as an M203, which was designed from the outset to fire explosive projectiles.2Office of the Law Revision Counsel. 26 USC 5845 – Definitions
How to Legally Buy One
A civilian transfer of a registered 40mm launcher runs through a Federal Firearms Licensee who holds Special Occupational Tax status for NFA firearms. The dealer files ATF Form 4 on your behalf, and the application includes your fingerprints, a recent photograph, identifying information, and a $200 transfer tax payment.3Bureau of Alcohol, Tobacco, Firearms, and Explosives. ATF Form 5320.4 (Form 4) – Application to Transfer and Register NFA Firearm
The $200 figure matters. As of 2026, that tax applies specifically to machine guns and destructive devices; other NFA items such as suppressors and short-barreled rifles now transfer at $0.4Office of the Law Revision Counsel. 26 USC 5811 – Transfer Tax
ATF runs the background check and, if the application is approved, records the launcher in the National Firearms Registration and Transfer Record. The dealer cannot release the launcher to you until the approved form comes back. As of February 2026, eForms applications for individual applicants are averaging around 10 days, with trust applications closer to 26 days. Paper submissions run a few weeks longer.5Bureau of Alcohol, Tobacco, Firearms and Explosives. Current Processing Times
Building Your Own on a Form 1
Federal law also lets you make your own NFA firearm, including a destructive device, if you file ATF Form 1 and get approval before you begin construction. The making tax is the same $200 that applies to a transfer. The application requires fingerprints, a photograph, and a background check, and a copy of the completed form must go to your local Chief Law Enforcement Officer. Once the launcher is built, you have to engrave it with your name, city, and state.6Bureau of Alcohol, Tobacco, Firearms, and Explosives. ATF Form 5320.1 – Application to Make and Register NFA Firearm
The Form 1 route suits hobbyists working from parts kits, but it is not a shortcut. You still end up with a registered destructive device subject to every rule that applies to a purchased one.
The Ammunition Problem
Ammunition is where 40mm ownership gets genuinely complicated. Individual explosive or incendiary 40mm rounds can each qualify as a separate destructive device, because a grenade carrying more than a quarter ounce of explosive charge meets the statutory definition on its own. That means each qualifying round would need its own $200 tax stamp and registration on top of the stamp for the launcher.7ATF eRegulations. 27 CFR 479.11 – Meaning of Terms
Explosive 40mm rounds also fall under federal explosives law. To acquire them you need either a Limited Permit, which allows receiving explosive materials from a licensee within your state on no more than six occasions in a one-year period, or a User Permit, which covers interstate transactions or more frequent purchases. Both require fingerprints, photographs, and a background check.8eCFR. 27 CFR Part 555 – Commerce in Explosives
For these reasons, most civilian 40mm owners stay with chalk practice rounds, smoke, or flare ammunition. Even some of those have drawn ATF scrutiny, with enforcement actions in certain cases treating 40mm chalk rounds as low explosives. Confirm the classification of any specific round with ATF before you buy it.
The 37mm Trap
Buyers often look at 37mm launchers as an unregulated alternative. A 37mm launcher designed and sold exclusively for flares, smoke, or pyrotechnics is generally treated as a signaling device outside the NFA. That status collapses the moment you pair the launcher with anti-personnel ammunition. Under ATF Ruling 95-3, a 37mm or 38mm flare gun possessed together with cartridges loaded with wood pellets, rubber balls, or bean bags becomes a destructive device requiring NFA registration.9Bureau of Alcohol, Tobacco, Firearms and Explosives. Destructive Device 26 USC 5845(f)(2) Owning the two together without a tax stamp is a felony.
State Bans Override Federal Approval
An approved federal tax stamp is not permission to possess a destructive device anywhere in the country. A small number of states prohibit destructive devices outright, so a registered 40mm launcher cannot legally be kept there regardless of your ATF paperwork. Others allow some categories and ban others, or leave the decision to local governments, and some layer their own permit requirements on top of the federal process. Verify your state’s rules through the state firearms regulator or an attorney familiar with NFA law before you buy or build.
Moving It Across State Lines
Federal law bars anyone other than a licensed importer, manufacturer, dealer, or collector from transporting a destructive device in interstate commerce without specific authorization from the Attorney General.10Office of the Law Revision Counsel. 18 USC 922 – Unlawful Acts
In practice you get that authorization by filing ATF Form 5320.20 with the NFA Division and waiting for approval before you travel. The approved form sets a time window for the trip, and if you ship the launcher by commercial carrier a copy has to travel with it. You also certify that possession at the destination is legal under that state’s laws, which puts the burden on you to know them.11Bureau of Alcohol, Tobacco, Firearms and Explosives. Application to Transport Interstate or to Temporarily Export Certain NFA Firearms
Storage When Explosive Rounds Are Involved
If you own explosive 40mm ammunition, federal explosives storage rules apply on top of NFA rules. Explosive materials must be kept in locked magazines that meet ATF specifications, indoor residential storage of high explosives is generally prohibited, and outdoor magazines have to sit at minimum distances from inhabited buildings, roads, and other magazines based on quantity. The owner has to physically inspect the storage at least every seven days for signs of tampering.8eCFR. 27 CFR Part 555 – Commerce in Explosives12Bureau of Alcohol, Tobacco, Firearms and Explosives. Explosives Storage Requirements
These requirements attach to the explosive materials, not the launcher itself. A registered 40mm launcher with only inert practice ammunition does not trigger the magazine rules, though normal secure storage still applies.
What Happens If You Get It Wrong
Possessing an unregistered NFA firearm, receiving one that was transferred illegally, transporting one across state lines without authorization, or altering serial numbers is a federal felony punishable by up to ten years in prison and a fine of up to $10,000.1Office of the Law Revision Counsel. 26 USC 5871 – Penalties13Office of the Law Revision Counsel. 26 USC 5861 – Prohibited Acts
The stakes rise sharply if the device is tied to a violent crime or drug trafficking offense. Using or carrying a destructive device during such a crime triggers a mandatory minimum of 30 years in federal prison, and a second such offense carries a mandatory life sentence.14Office of the Law Revision Counsel. 18 USC 924 – Penalties Converting a 37mm signaling launcher to fire 40mm rounds, keeping anti-personnel ammunition alongside an unregistered flare launcher, or skipping the registration paperwork can each land you in this territory, and ignorance of the classification rules is not a defense.