The guy checking your weapons at the door might suggest something else, but you definitely want to give him the impression that yo are safety conscious
For walking around the show, I suggest carrying them in your backpack with a "For Sale" sign attached to the pack indicating what you're selling. See it all the time.
You'll need to check them at the door with security, and for this, you'll want to have the guns unloaded (obviously), actions locked open, and preferably zip-ties looped through the barrel and/or magazine wells and chambers. Do something similar through the cylinder and barrel of any revolvers. The guy checking your weapons at the door might suggest something else, but you definitely want to give him the impression that yo are safety conscious.