Reply #77: There is no set number

[one-eyed fat man]

A person who does not have a Federal Firearms License may not be in the business of buying or selling firearms. Individuals buying and selling firearms without a federal license must be doing so from their own personal collection.

Engaged in the Business (Firearms) Law & Legal Definition

(C) as applied to a dealer in firearms, as defined in section 921(a)(11)(A) <18 USCS § 921(a)(11)(A)>, a person who devotes time, attention, and labor to dealing in firearms as a regular course of trade or business with the principal objective of livelihood and profit through the repetitive purchase and resale of firearms, but such term shall not include a person who makes occasional sales, exchanges, or purchases of firearms for the enhancement of a personal collection or for a hobby, or who sells all or part of his personal collection of firearms;

If a person sells a large number of guns that might make it easier to prove. Even if a seller loses money "through the repetitive purchase and resale of firearms" he could still be considered "in the business" there is no requirement he be good at it.

Some states have laws defining someone as a dealer for the singular purpose of collecting taxes. For example, one state defines a car dealer as:

"A person who sells three or more motor vehicles in any period of 12 months is required to hold a seller’s permit."

Dealers are required to collect, and more importantly pay, the sales taxes on the car they sell where an occasional sale is exempt. They just pick a number to make it easier to enforce.

That practice is pretty common but does not apply to guns under Federal law.