A simplified diagram of a hypothetical gun show with 5 rows of vendors. An area just inside the entrance to the event commonly served as a marketplace for private party gun sales, but they also occurred elsewhere. While most vendors occupied a single display table, larger vendors took up several adjoining tables and in some cases fronted more than one row of the show.

Not all vendors sold guns (other products commonly sold included ammunition, knives and swords, and gun parts).

Gun vendors were vendors occupying 1 or more display tables and offering 5 or more guns for sale or selling fewer guns that occupied at least 1/3 of their display space.

Licensed firearm retailers were gun vendors who displayed a federal firearms license, had business cards identifying them as licensed retailers, or at whose table(s) the forms required when buying firearms from a licensed retailer were observed. When none of these criteria was met, a transaction was observed if possible to see if the forms were produced at that time.

Individual attendees were persons in the customer space of the show. Guns brought to the show by armed attendees were clearly marked by staff at the entrance to indicate this.

Armed attendees often had “For Sale” signs affixed to their guns or to themselves and carried the guns prominently so as to attract attention to them. Attendees whose guns were marked as having been sold to them by a vendor at the show were not classified as armed attendees.

A private party gun sale was defined as a sale between a gun vendor and attendee, or between attendees, that did not include completing the forms required for a purchase from a licensed retailer. A gun sale was classed as a straw purchase only if the purchase was made from a licensed retailer, the required forms were completed, and there was clear evidence that the person purchasing the firearm was not the intended possessor.

Attendees were often observed conducting cellphone conversations about guns they were examining and using their phones to photograph the guns. Purchases associated with these activities were not classified as straw purchases.