I was wondering the same thing. They still check at the gun show right? What law authorizes this search?
No law that I know of, unless they're saying the Cobb Civic Center is a government building or something. I think it's probably the same thing as with this state fair...private property rights trump your right to carry, so if the gunshow promoter or owner of the building says no carry, then it's no carry. You wouldn't be arrested if they found it on you, but you wouldn't be allowed to enter.