No need to stir the pot, you can just do it and not tell anyone. They can not prohibit it, however they can write a new rule that says you have to tell them you are doing it if you bring it up. So if you are going to do it, keep quiet but be aware Ohio is an at will state. So they can fire you for any reason at all. But if they specifically say they are firing you for the gun in your car you will win that lawsuit in a heartbeat. But if they fire you because of the gun, but never mention the gun and say it's because we don't like you...you are SOL.