NFA & ATF Glossary

A

AOW (Any Other Weapon)

A catch-all NFA category for weapons that don't fit other classifications. Includes smooth-bore pistols, pen guns, cane guns, and firearms with vertical foregrips on pistol frames. AOW transfers have a reduced $5 tax stamp (vs $200 for other NFA items).

ATF (Bureau of Alcohol, Tobacco, Firearms and Explosives)

The federal agency responsible for regulating NFA items, processing Form 1 and Form 4 applications, and conducting background checks on NFA applicants. Part of the Department of Justice.

Approved / Approval

When the ATF completes your background check and authorizes your Form 1 or Form 4. You'll receive a stamped copy of your form, and can take possession of your NFA item (Form 4) or begin manufacturing (Form 1).

B

Background Check

The FBI NICS check conducted on all NFA applicants. Includes review of criminal history, mental health records, and other disqualifying factors. This is why fingerprints are required—they're compared against FBI databases.

Batch Approval

When multiple Form 4s submitted around the same time by the same applicant are approved together. Common for trust applications with multiple items pending.

Beneficiary

In an NFA trust context: a person named to inherit or benefit from trust assets. Under 41F, beneficiaries with power over trust property must submit fingerprints and photos.

C

CLEO (Chief Law Enforcement Officer)

The top law enforcement official in your jurisdiction (sheriff, chief of police). NFA applicants must notify their CLEO of pending applications. Prior to 41F, CLEO signature was required—now only notification is needed. See our CLEO lookup tool.

CLEO Notification

The requirement to send a copy of your Form 1 or Form 4 to your local CLEO. This is notification only—they cannot approve or deny your application. Most people mail a copy to the sheriff's office.

Controlled (NFA Item)

Items regulated under the National Firearms Act that require registration, tax payment, and ATF approval to manufacture or transfer. Includes suppressors, SBRs, SBSs, machine guns, destructive devices, and AOWs.

D

Dealer (SOT/Class 3)

A Federal Firearms Licensee (FFL) with Special Occupational Tax status who can deal in NFA items. When you buy a suppressor, it ships to a dealer who holds it until your Form 4 is approved.

Destructive Device (DD)

An NFA category including explosive devices (grenades, bombs) and firearms with bore diameter over 0.50 caliber (excluding shotguns). Regulated the same as other NFA items.

DPI (Dots Per Inch)

A measure of image resolution. For fingerprint scanning, 500 DPI is the minimum for EFT conversion; 600 DPI is recommended. Higher DPI captures more fingerprint ridge detail.

E

eFile / eForms

The ATF's electronic filing system at eforms.atf.gov. Allows online submission of Form 1, Form 4, and other applications. Faster processing than paper forms. Requires electronic fingerprint submission (EFT files).

EFT (Electronic Fingerprint Transmission)

A digital file format containing fingerprint images and biographical data. Used for electronic submission to ATF eForms. SlapEFT converts paper FD-258 cards into EFT files. File extension is typically .eft

Engrave / Engraving

The requirement to mark NFA items with manufacturer information. For Form 1 builds, you must engrave your name/trust name, city, and state to a depth of 0.003" and height of 1/16". Must be done before or when making the item.

Examiner

The ATF employee who reviews your Form 1 or Form 4 application, checks your background, and makes the approval decision. You'll never interact with them directly.

F

FD-258

The standard fingerprint card used for FBI background checks and ATF applications. White card with spaces for 10 fingerprints (rolled and flat impressions) plus biographical data. Can be obtained from law enforcement, UPS stores, or purchased blank. See our FD-258 Guide.

FFL (Federal Firearms Licensee)

A business or individual licensed by the ATF to deal in firearms. All commercial gun dealers are FFLs. NFA items must be transferred through an FFL with SOT status.

Flat Prints / Slap Prints

Fingerprints taken by pressing fingers flat against a surface (as opposed to rolled prints). FD-258 cards include both rolled and flat impression areas. EFT Type-14 format is specifically for flat prints.

Form 1 (ATF Form 5320.1)

Application to Make and Register a Firearm. Used when you're building/manufacturing an NFA item yourself—like assembling an SBR from a pistol lower or building a suppressor from a kit. Requires $200 tax payment.

Form 3 (ATF Form 5320.3)

Application for Tax-Exempt Transfer of Firearm. Used for dealer-to-dealer transfers. When you buy a suppressor online, the Form 3 moves it from manufacturer to your local dealer.

Form 4 (ATF Form 5320.4)

Application for Tax Paid Transfer and Registration of Firearm. Used when purchasing an NFA item from a dealer. The most common form for buying suppressors, SBRs, etc. Requires $200 tax payment.

Form 5320.23

Responsible Person Questionnaire. Required for each responsible person on a trust or corporation NFA application. Includes questions about citizenship, criminal history, and other eligibility factors.

G

Grantor

The person who creates and funds an NFA trust. Also called the settlor. Usually the primary beneficiary and trustee as well.

Gun Trust

See: NFA Trust

I

Individual (Applicant Type)

One of three ways to register NFA items. When applying as an individual, only you can possess the item. Simpler than a trust but less flexible for estate planning and sharing.

In Jail

Slang for the period when your suppressor or NFA item is at the dealer waiting for Form 4 approval. "My can has been in jail for 6 months."

L

Live Scan

Electronic fingerprint capture using a digital scanner. Produces EFT files directly without paper cards. Available at UPS stores, some law enforcement agencies, and dedicated fingerprint services. Alternative to scanning FD-258 cards.

M

Machine Gun

A firearm that fires more than one round per trigger pull. NFA category. Civilian ownership limited to machine guns manufactured and registered before May 19, 1986 (Hughes Amendment). These "transferable" machine guns are expensive ($10,000+).

Make (Manufacturing)

In ATF terms, to create or assemble an NFA item. Form 1 is the "Application to Make." Engraving an SBR lower before adding a short barrel is "making" the firearm.

N

NFA (National Firearms Act)

The 1934 federal law establishing registration and tax requirements for certain firearms. Amended over the years, it's the legal framework for suppressor, SBR, SBS, and machine gun ownership. Administered by the ATF.

NFA Branch

The division of the ATF that processes Form 1, Form 4, and other NFA applications. Located in Martinsburg, West Virginia. The people who actually review your paperwork.

NFA Trust

A legal trust specifically designed for owning NFA items. Benefits include: multiple trustees can possess items, easier estate planning, and no CLEO signature requirement (pre-41F). Post-41F, all responsible persons must submit fingerprints. See our NFA Trusts page.

NICS (National Instant Criminal Background Check System)

The FBI database used for firearm background checks. NFA applicants undergo an enhanced check beyond standard NICS, explaining the longer wait times.

NIST (National Institute of Standards and Technology)

Federal agency that establishes technical standards, including fingerprint file formats. "NIST-ITL compliant" means a file meets their specifications for electronic fingerprint transmission.

NIST-ITL

The technical standard (ANSI/NIST-ITL) for biometric data interchange. Specifies exactly how EFT files must be formatted, what data fields are required, and how fingerprint images must be encoded.

O

ORI (Originating Agency Identifier)

A 9-character code identifying the agency requesting fingerprint checks. For personal ATF submissions, you typically don't need to provide this—it's assigned by the agency.

P

Paper Form

Traditional method of submitting ATF forms by mail with physical fingerprint cards. Slower than eForms (often 12+ months). Requires mailing two FD-258 cards per responsible person.

Pending

Status of an NFA application that has been submitted and is awaiting approval. "My Form 4 has been pending since January." Track current wait times on our Processing Times page.

Possession

Physical control of an NFA item. Only registered owners (or trust members) can possess NFA items. Lending your suppressor to a friend—even briefly—is illegal unless they're on your trust.

R

Responsible Person (RP)

Under ATF Rule 41F, any individual who can direct or control trust/corporation activities. For NFA trusts, this typically includes trustees and some beneficiaries. Each RP must submit fingerprints and photos with every application.

Rolled Prints

Fingerprints captured by rolling each finger from nail to nail, capturing the full ridge pattern. Used by law enforcement for more detailed records. EFT Type-4 format. FD-258 cards have space for both rolled and flat prints.

Rule 41F (41P)

ATF rule effective July 2016 that changed NFA trust requirements. Eliminated CLEO signature requirement but added fingerprint/photo requirements for all responsible persons. Named after the federal register section.

S

SBR (Short Barreled Rifle)

A rifle with a barrel under 16" or overall length under 26". NFA regulated item. Created by Form 1 (making from a pistol) or Form 4 (purchasing factory SBR). $200 tax stamp required.

SBS (Short Barreled Shotgun)

A shotgun with a barrel under 18" or overall length under 26". NFA regulated. Less common than SBRs due to limited practical applications. $200 tax stamp required.

Settlor

The person who creates a trust. Also called grantor. In NFA trust context, usually the initial and primary trustee.

Silencer

Legal term for suppressor. The NFA uses "silencer" officially, though "suppressor" is more technically accurate (they reduce, not eliminate, sound). Both terms are correct.

SOT (Special Occupational Tax)

Annual tax paid by FFLs to deal in NFA items. Class 1 for importers, Class 2 for manufacturers, Class 3 for dealers. "Class 3 dealer" is common shorthand.

Suppressor

Device attached to a firearm to reduce sound and muzzle flash. NFA regulated. The most commonly purchased NFA item. Also called silencer, can, muffler. $200 tax stamp required.

T

Tax Stamp

The $200 federal tax paid when making (Form 1) or transferring (Form 4) an NFA item. Upon approval, a physical or digital stamp is affixed to your form. Proof of legal registration. AOW transfers are only $5.

Transfer

Moving possession of an NFA item from one registered owner to another. Requires ATF approval (Form 4) and $200 tax payment. Includes sales, gifts, and inheritance.

Trustee

A person designated to manage trust assets. In NFA trusts, trustees can possess and use the trust's NFA items. All trustees are responsible persons requiring fingerprint submission.

Type-4 (Record Type 4)

NIST-ITL record type for grayscale rolled fingerprint images. Created by live scan devices that roll each finger. Used by law enforcement. ATF accepts Type-4 files.

Type-14 (Record Type 14)

NIST-ITL record type for flat/slap fingerprint images. What FD-258 cards capture. What SlapEFT generates. ATF accepts Type-14 files. Standard for converted fingerprint cards.

W

Wait Time

The period between submitting an NFA application and receiving approval. Currently 30-90 days for eForm 1, 90-180 days for eForm 4. Varies based on ATF workload. Check our Processing Times Tracker.

WSQ (Wavelet Scalar Quantization)

The FBI's fingerprint image compression standard. Designed to maintain ridge detail while reducing file size. EFT files use WSQ encoding at approximately 15:1 compression ratio. SlapEFT uses FBI-compliant WSQ compression.