You just can't have a loaded weapon or loose ammo on you. A few years ago there was a little boy, about 7-9 years old that was accidentally shot in the head by a dumbass vendor trying to his gun to the boys father. The boy died. As long as I have been going to gun shows (30 plus years), it has always been no loaded firearms or loose ammo allowed by attendees. The vendors are allowed to have loaded and holstered.
Also, the selection of customers at the gun shows has changed a lot. Walk behind some of these people and you have a good chance to get a contact high from them blazing up before coming in.