Is It Legal to Build Your Own Suppressor? Form 1 and Engraving

Yes, it is legal to build your own suppressor under federal law, but only after the ATF approves your ATF Form 1 application and you pay a $200 making tax. Build first and file later, and you have committed a federal felony carrying up to ten years in prison. Eight states and the District of Columbia ban civilian suppressor ownership entirely, so federal approval does you no good if you live in one of them.

Where You Live Decides Half the Question

Federal approval does not override state law. California, Delaware, Hawaii, Illinois, Massachusetts, New Jersey, New York, and Rhode Island prohibit civilian suppressor ownership, as does the District of Columbia. Building a suppressor in any of these places is illegal even with an approved Form 1 in hand. The other 42 states allow it, though some layer their own registration or permit requirements on top of the federal ones. Confirm your state and local rules before you file anything.

Who Can Legally Apply

A suppressor is a firearm under the National Firearms Act of 1934, and the same federal disqualifiers that bar someone from owning a gun bar them from building a suppressor.¹ You cannot legally build or possess a suppressor if you:

Have a felony conviction, meaning any crime punishable by more than one year in prison, in any court
Are a fugitive from justice
Use or are addicted to a controlled substance
Have been adjudicated mentally defective or committed to a mental institution
Are in the United States unlawfully
Received a dishonorable discharge from the military
Have renounced U.S. citizenship
Are subject to a qualifying domestic restraining order
Have a misdemeanor domestic violence conviction

Being under federal indictment for a felony-level crime also bars you from receiving or transporting firearms while the indictment is pending.² Form 1 asks about each category, and lying on the form is itself a federal crime.

Filing ATF Form 1

The legal gateway is ATF Form 1, “Application to Make and Register a Firearm.” You cannot begin construction until the form is approved and the tax stamp is returned to you. The application collects your personal information, a description of the suppressor you plan to build (caliber, overall length, and a serial number you assign), and the $200 making tax.³

Fingerprints, Photo, and CLEO Notice

You can submit Form 1 electronically through the ATF eForms system or on paper by mail to the NFA Division.⁴ Either route requires two fingerprint cards (FBI Form FD-258) and a passport-style photograph taken within six months of filing. Electronic filers can upload a digital fingerprint file in EFT format; if you use paper cards with an electronic submission, those cards must reach the NFA Division within ten days.⁵

You must also send a copy of your application to your local Chief Law Enforcement Officer. This is a notification, not a permission request. The CLEO has no power to block your application, but the ATF will not process a Form 1 without confirmation the notice went out.

Filing Through a Gun Trust

Many applicants file through an NFA gun trust rather than as individuals. The advantage is shared possession: every responsible person named in the trust can legally possess the suppressor, while an individually registered item can only be possessed by the registered owner. The cost is paperwork. Each responsible person listed must submit their own fingerprints, photograph, and an ATF Form 5320.23 (Responsible Person’s Questionnaire), plus a separate CLEO notification copy.³

How Long It Takes

As of February 2026, the ATF reports average processing times of about 36 days for electronic Form 1 submissions and roughly 20 days for paper.⁶ Volume and background-check flags can push individual applications longer. When it is approved, the ATF affixes the tax stamp and returns the form. That approved document is your proof of registration. Keep it permanently.

Do Not Buy Parts Before Approval

The federal definition of “silencer” is broader than a finished device. It also covers any combination of parts designed for assembling a suppressor, and any individual part intended solely for that purpose.⁷ Stockpiling baffles, end caps, and tubes while you wait for your paperwork is a federal offense on its own.

This is where solvent trap kits catch people. In a 2023 open letter, the ATF stated that the label a seller puts on a product does not matter: if the device has objective design features indicating it is meant to reduce the sound of a gunshot, it is a silencer under federal law.⁷ A component does not have to be fully functional to qualify. A baffle with a mark showing where to drill a hole is enough.

The critical consequence: a solvent trap that meets that definition was “manufactured” by the company that sold it, not by you, and that company almost certainly did not register it. An unregistered NFA firearm cannot be retroactively registered by the person who possesses it. Your approved Form 1 does not fix the problem, because the suppressor was already made before it reached you.⁷ The safe path is to build from raw materials you machine yourself, or to buy components from a manufacturer who has properly registered them.

Building It: Engraving and Marking Rules

Once your Form 1 is approved, you can build the suppressor. Before you use it, you must permanently mark the outer tube (the serialized part) with:

The serial number you specified on your Form 1
Your name, or a recognized abbreviation, as the maker
The city and state where you made it
The caliber, engraved on the frame, receiver, or barrel
A model designation, if you assigned one

All markings must be engraved, cast, or stamped to a minimum depth of .003 inches, and the serial number must be in a print size no smaller than 1/16 of an inch.⁸ They must be placed where they cannot be easily removed or altered. Most home builders use a professional engraving service. Failing to properly mark a suppressor you built is a standalone federal offense, separate from any other violation.⁹

Repairs After the Build

Internal components like baffles can only be replaced by a currently licensed Special Occupational Taxpayer (SOT) manufacturer, not by you as the registered owner. Replacement is one-for-one, the original part is destroyed, and the new part must match the original dimensions exactly.¹⁰

You can repair the outer tube yourself as long as the repair does not remove, change, or obscure the serial number. If the tube is damaged beyond repair, you can fabricate a replacement, but you must file a new Form 1 and pay another $200 tax. The replacement tube must carry all required markings (you can reuse the same serial number). Reassembling it with the original internal parts does not require a second Form 1.¹⁰

Transferring It Later

A suppressor built on a Form 1 is registered to you (or to your trust). You can transfer it, but the recipient must file ATF Form 4, pay their own $200 transfer tax, and submit fingerprints and photographs. The ATF must approve the transfer before the suppressor changes hands.¹¹ For a transfer to someone in a different state, the item must move through a federally licensed dealer holding SOT status. You cannot mail or carry a suppressor across state lines to a friend, even if both states allow suppressors.

What Happens If You Skip a Step

NFA violations are federal felonies. The statute prohibits making a suppressor without approval, possessing one that is not registered to you, transferring one outside the legal process, and tampering with serial numbers or other markings.⁹

A conviction carries up to ten years in federal prison.¹² The original NFA set the maximum fine at $10,000, but a later amendment to general federal sentencing law raised that ceiling to $250,000 for individuals.¹³ The government can also seize and forfeit the suppressor and any firearm used with it. There is no procedure to register an unregistered NFA firearm after the fact.¹ In states that ban suppressors, state charges stack on top of the federal ones.

1
Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF). National Firearms Act
2
Office of the Law Revision Counsel. 18 USC 922 – Unlawful Acts
3
Bureau of Alcohol, Tobacco, Firearms, and Explosives. Application to Make and Register a Firearm – ATF Form 5320.1
4
Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF). eForms Applications
5
Bureau of Alcohol, Tobacco, Firearms and Explosives. NFA Form One Submission External Guidance
6
Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF). Current Processing Times
7
Bureau of Alcohol, Tobacco, Firearms and Explosives. Open Letter to All Federal Firearms Licensees – Solvent Trap Devices
8
eRegulations – ATF eRegulations. 27 CFR 479.102 – Identification of Firearms
9
Office of the Law Revision Counsel. 26 USC 5861 – Prohibited Acts
10
Regulations.gov. ATF Letter Regarding Silencer Marking and Repair
11
Bureau of Alcohol, Tobacco, Firearms and Explosives. NFA Handbook – Chapter 9 – Transfers of NFA Firearms
12
Office of the Law Revision Counsel. 26 USC 5871 – Penalties
13
Bureau of Alcohol, Tobacco, Firearms and Explosives. NFA Handbook – Chapter 15 – Penalties and Sanctions