That's not 100% correct.BigBangSmallBucks wrote: If a Non-TSA lock is used TSA has the authority to cut it, . . .
If it is a hard-sided case with a declared firearm they do not have that authority. Legally, you (gun owner) are required to have all the keys for the duration of the journey (you can unlock the case for the TSA) and since most TSA employees are not allowed to have weapons on the job, cutting a gun case lock (and thus taking possession of your gun) can line them up for trouble. They have the authority to call you back to screening to unlock the case.
Of course if they mess up and forget to read the tag before cutting it can be a hassle for you, too, because an unlocked gun case cannot fly. Best case (heh), you have a spare padlock. Worst case, you get pulled off the plane and miss your flight.
I have had TSA locks messed with. I have never had padlocks on a gun case harmed (I have been asked to unlock). I once had a TSA person who saw me carrying a padlocked pelican "warn" me that the lock would be cut. I replied, "gun case." He replied, "oh..."
Legally, it seems clear you cannot use TSA locks on a gun case due to the requirement that you keep control of the keys.