Drawing a gun at the ticket counter is NOT the way to handle things for anyone who wants to make his flight. There is NO good reason to do this, since the gun has to be unloaded and in a locked container in your luggage before it goes to TSA inspection.
My experience and interpretation of the rules: If you have a locked gun case inside a suitcase, the suitcase does not have to be locked, and, if it is, any old kind of lock is accepted.