Gun Transfer & Firearms Glossary: FFL, NICS, 4473, NFA and More

This glossary defines the terms that come up when you buy, transfer, sell, or carry a firearm in the United States. It is written for the person who needs to know what a form number, an acronym, or a legal category means in plain language, without wading through 40 pages of ATF regulations. If a term you are looking for is not listed, tell us at hello@guntransfers.com and we will add it.

Regulatory terms

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

The federal agency that licenses firearms dealers, enforces the Gun Control Act and the National Firearms Act, and audits FFL records. Every dealer on GunTransfers.com is an active ATF licensee.

FFL (Federal Firearms License)

The license that lets a person or business engage in the firearms trade, whether that is retail sales, manufacturing, importing, or dealing in NFA items. An “FFL” in everyday conversation almost always means “an FFL dealer,” the person who runs the transfer paperwork on your behalf. GunTransfers.com lists roughly 55,000 active FFL dealers across all 50 states.

FFL types (01, 02, 03, 07, 08, 09, 10, 11)

The ATF issues nine license types. Types 01 (dealer) and 02 (pawnbroker) handle the vast majority of retail transfers. Type 03 is the Curio and Relic license for collectors of firearms 50+ years old. Types 07, 08, 10, and 11 cover manufacturers and importers.

ATF Form 4473

The Firearms Transaction Record. Every buyer fills one out at the receiving FFL before a firearm leaves the counter. The dealer keeps it on file for at least 20 years and turns it in to the ATF if the shop closes. Lying on a 4473 is a federal felony under 18 U.S.C. 922(a)(6).

NICS (National Instant Criminal Background Check System)

The FBI-run check the FFL runs on the buyer while the 4473 is being processed. Most checks return a “Proceed” in under two minutes. A “Delay” can hold the transfer for up to three business days; a “Denied” stops it. Roughly 30 million NICS checks run per year in the United States.

GCA (Gun Control Act of 1968)

The federal law that created the FFL system, set the minimum ages for firearm purchase (18 for a long gun, 21 for a handgun from an FFL), and banned interstate handgun sales to non-dealers. It is why an out-of-state purchase has to route through an FFL in your home state.

NFA (National Firearms Act of 1934)

The 1934 law that regulates suppressors, short-barreled rifles, short-barreled shotguns, machine guns, destructive devices, and “Any Other Weapons.” NFA items require a $200 tax stamp (except AOWs at $5), ATF Form 4 approval, and a wait that currently runs six to nine months.

SOT (Special Occupational Tax)

The annual tax an FFL pays to deal in NFA items. Class 3 SOT dealers are the ones you go through for suppressors and short-barreled rifles. Not every FFL is an SOT; if you are buying NFA, filter for Class 3 dealers on GunTransfers.com.

C&R (Curio and Relic)

A Type 03 FFL held by collectors. It lets the holder receive C&R-eligible firearms (generally 50+ years old) directly at their home instead of routing through a retail FFL. It is not a dealer’s license; C&R holders cannot sell to the public as a business.

Transfer and purchase

FFL transfer

The act of moving a firearm from a seller to a buyer through a licensed dealer. The dealer accepts the shipment, logs it into their Acquisition and Disposition record, runs the 4473 and NICS on the buyer, and hands over the firearm. Fees usually run $25 to $75 per transfer. Find one near you on Find a Dealer.

Interstate transfer

A firearm sold from a seller in one state to a buyer in another has to route through an FFL in the buyer’s home state. This is why the online gun store ships to the FFL, not to your house. Long guns can be purchased in person out of state at an FFL that follows both states’ laws; handguns cannot.

Face-to-face transfer

An in-person sale between two private residents of the same state. Federal law allows this without an FFL. State law is where it gets specific: California, Colorado, New York, Washington, and about a dozen others require the sale to still route through an FFL. Check your state hub on GunTransfers.com.

Private transfer

Any transfer between two non-dealers. Federal law does not require a background check on a private in-state sale; universal background check states do. If either party is not a resident of the state where the transfer occurs, an FFL is always required.

Straw purchase

Buying a firearm on behalf of someone else who cannot legally purchase it themselves. This is a federal felony (18 U.S.C. 922(a)(6)) and question 21a on the 4473 asks it directly. A legal gift is not a straw purchase; the intent to transfer to a prohibited person is what makes it one.

Universal background check

A state requirement that every firearm transfer, including private sales between residents, go through NICS via an FFL. As of 2026, about 22 states plus DC require it in some form. In the rest, private in-state sales are not federally required to run a check.

Waiting period

A state-imposed delay between purchase and pickup. Nine states currently impose one (California’s is 10 days; Illinois splits handguns and long guns). The federal minimum is zero. The waiting period runs alongside NICS, not instead of it.

Transfer fee

What the receiving FFL charges to handle your inbound firearm. National average sits around $35. High-volume dealers list $25 or less; some boutique shops charge $75+. Rates and any add-ons (NICS proceed fee, storage, NFA handling) are shown on each dealer’s profile page on GunTransfers.com.

Firearm classes

Handgun

A pistol or revolver designed to be fired with one hand. Federal minimum age to buy from an FFL is 21. Cannot be sold across state lines to a non-dealer without routing through the buyer’s home-state FFL.

Long gun

Rifle or shotgun with a barrel of at least 16 inches (rifle) or 18 inches (shotgun), designed to be fired from the shoulder. Federal minimum age 18. Can be purchased in person at an out-of-state FFL if the sale meets both states’ laws.

Suppressor (silencer)

An NFA-regulated device that reduces the report of a firearm. Requires a $200 tax stamp, ATF Form 4, and a Class 3 SOT dealer to run the transfer. Approvals currently run 6 to 9 months. Legal to own in 42 states.

SBR (short-barreled rifle)

A rifle with a barrel under 16 inches or an overall length under 26 inches. NFA-regulated, $200 tax stamp, Form 4. An AR-style pistol with a stabilizing brace is legally not an SBR; the ATF rule that would have reclassified them was vacated in federal court in 2024.

SBS (short-barreled shotgun)

A shotgun with a barrel under 18 inches or overall length under 26 inches. NFA-regulated, same $200 stamp and Form 4 as an SBR.

AOW (Any Other Weapon)

An NFA catch-all: pen guns, cane guns, wallet holsters that fire, smooth-bore pistols, disguised firearms. Tax stamp is $5 to transfer instead of $200. Manufacturing tax is still $200.

Machine gun

A firearm that fires more than one round per trigger pull. Civilian ownership is restricted to machine guns registered before May 19, 1986 (Hughes Amendment). Registered pre-86 machine guns are legal to own in most states and trade in a fixed, appreciating market.

Antique firearm

Any firearm manufactured on or before 1898, and any replica of one that does not use fixed ammunition. Federally exempt from the FFL system: no 4473, no NICS, ships to your door. State law may still apply.

Carry and ownership

Concealed carry (CCW, CHL, CPL, LTC)

Carrying a concealed firearm on your person. The permit is called different things by state (CCW in most, CHL in Texas and Oregon, CPL in Michigan, LTC in Massachusetts). Requirements range from a background check and $20 fee to a training course, live-fire test, and interview.

Constitutional carry

A state law that lets a legally-eligible resident carry a concealed firearm without a permit. As of 2026, 29 states are permitless-carry or constitutional-carry states in some form. A permit is still useful for reciprocity when traveling.

Open carry

Carrying a firearm visibly. Legal without a permit in most states, restricted or banned in California, Florida (as of 2026 Florida is open-carry legal for permit holders), New York, Illinois, Massachusetts, and DC.

Reciprocity

Whether one state honors another state’s concealed carry permit. Reciprocity is a moving target. USCCA and Handgunlaw.us maintain updated maps. A Utah non-resident permit is recognized in the largest number of states as of 2026.

Concealed carry insurance

Coverage for the legal costs if a lawful self-defense incident results in criminal or civil proceedings. A typical defensive-gun-use case can run $20,000 to $200,000 in legal fees even when charges are dropped. USCCA is the largest carrier in the category and is the standard reference when people say “CCW insurance.”

Red flag law (ERPO)

An Extreme Risk Protection Order lets a family member or law enforcement petition a court to temporarily remove firearms from someone deemed a danger to themselves or others. 21 states plus DC have red flag laws as of 2026. Procedures and appeal rights vary widely by state.

Permit to purchase

A state-issued permit that must be obtained before buying a handgun or, in a few states, any firearm. Required in Illinois (FOID), New Jersey (FPIC), Massachusetts (FID/LTC), New York, Iowa, Michigan, Minnesota, North Carolina, and a handful of others. Federal law does not require one.

Parts and components

Receiver (lower / upper)

The serialized part of a firearm. On a bolt-action rifle it is the receiver. On an AR-15 it is the lower receiver; the upper (which contains the barrel and bolt) is not serialized and is not a firearm under federal law. A “firearm” for legal purposes is whichever part carries the serial number.

Stripped lower

An AR-style lower receiver sold without any parts installed. Legally a firearm; requires a 4473, NICS, and (if bought online) an FFL transfer. Age requirement is 18 for a stripped lower even though a finished AR is a rifle.

80% lower

An unfinished receiver that requires the buyer to complete final machining to make it functional. Under federal rules finalized in 2022 and revised in court in 2024, an 80% kit that includes the jigs and tools is treated as a firearm and requires an FFL transfer. A blank forging is not.

Ghost gun

A privately-made firearm without a serial number. Federally legal to build for personal use; illegal to manufacture for sale without an FFL. Several states (California, New York, Washington, others) require serialization and registration.

Serial number

The unique identifier stamped on the receiver of every commercially-manufactured firearm since the Gun Control Act of 1968. Removing, altering, or obliterating it is a federal felony under 18 U.S.C. 922(k).

Magazine capacity limit

A state cap on the number of rounds a detachable magazine can hold. Ten rounds is the most common limit. States with capacity limits include California, Colorado, Connecticut, DC, Hawaii, Illinois (12 for handguns), Maryland, Massachusetts, New Jersey (10), New York (10), Oregon (10 as of 2024), Vermont, and Washington. Federal law does not limit magazine capacity.

Bump stock

A stock accessory that harnesses recoil to enable rapid semi-automatic fire. Banned by ATF rule in 2018; that rule was struck down by the Supreme Court in Garland v. Cargill (2024). Federally legal again; some states (California, Delaware, Florida, Hawaii, Massachusetts, New Jersey, New York, Rhode Island, Vermont, Washington) still ban them.

Marketplace terms

Online gun store

A retailer that lists inventory online and ships to your local FFL. The buyer is not receiving the firearm in the mail. Guns.com, GunBroker, Palmetto State Armory, and Brownells are among the largest by volume. The store handles shipment to the FFL; you handle the 4473 and transfer fee at pickup.

Auction site

A firearms auction marketplace like GunBroker or GunsInternational. The winning bidder pays the seller, and the seller ships to the winner’s FFL. The auction site is not an FFL.

Cerakote, bluing, parkerizing

Firearm finishes. Cerakote is a modern ceramic-polymer coating available in almost any color. Bluing is the traditional black-oxide finish. Parkerizing is a phosphate finish common on military-surplus firearms. None of the three affects the classification or transfer requirements.

What to do with this

If you are about to buy or sell a firearm across state lines, the specific term you need to know is FFL transfer. Start on Find a Dealer, filter by state and city, and compare transfer fees on the dealer profile pages. Every listing on GunTransfers.com is a verified active FFL, and the state hubs (Texas, California, Florida, and 47 others) cover the state-specific rules that override the federal minimums summarized above.

If you already own a firearm and carry it, the term to know is concealed carry insurance. A single defensive-gun-use incident that goes to trial can outrun a homeowners policy in a week. USCCA is the largest and most widely-recognized provider in the category; the USCCA lays out the tiers.

Missing a term? Email hello@guntransfers.com. We add requested definitions in the weekly content update.