I was at Six Flags recently, and was carrying a gun-style fanny pack (but had no firearms on me). It was just a place to place some things for my bride who didn't bring her purse. I walked through the metal detector, and they looked inside the pack and waved me through. After going in the park, another guard stopped me to take a look in it. In both cases I could have been carrying under my shirt or in an ankle holster. I was not required to remove any items to go back through the metal dectector.