You need a type 1 Federal Firearms License to deal in firearms. There are multiple types, but type 1 what is required to firearms for a living.
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You still need a Type 2 FFL to operate as a pawnbroker. A Type 1 covers gunsmiths and dedicated gun stores - Type 2 is exclusive to pawnbrokers. As a Type 1 FFL holder, I can say this with absolute certainty.
Perfectly legal- IF the Pawn Shop has an 02 Federal Firearms License, AND you are old enough and legally able to possess a firearm, AND you have a government issued photo ID that shows your name, age and address. The pawn shop must comply with Federal laws, and before returning a redeemed gun must conduct a background check. Not all pawn shops have a Federal Firearms License, and those shops cannot pawn or sell guns.
Federal Firearms License
As of 2012, there were 51,438 retail gun stores, and 7,356 pawn shops with a gun dealer's license. There are about 62,000 collectors with a Federal Firearms license.
Federal Firearms License.
You may pawn a firearm you own at a pawnshop that has a firearms license- not all pawn shops do.
You have to be 21 to get a Federal Firearms License in ANY US state, territory, or protectorate.
In the US, you apply for a business license and apply to the Bureau of Alcohol, Tobacco, Firearms and Explosives for an 01 Federal Firearms License (Dealer's license).
The letters FFL stand for a Federal Firearms License. This is a license that enables an individual or a company to legally manufacture firearms or ammunition.
In most cases, no. However, a theft from an interstate shipment of firearms, or theft from a Federal Firearms License holder (dealer or manufacturer) IS a Federal offense.
The Bureau of Alcohol, Tobacco, Firearms and Explosives web site has the information that you are looking for.
The sale of firearms is governed by both State and Federal laws. To be "engaged in the business" of buying and selling guns anywhere in the US, you must be licensed by the Federal Government as a Federal Firearms License holder with an 01 Dealers license. All gun shops and sporting goods stores that sell firearms hold such a license.
You will have to contact the BATFE to fnd out.