Obviously this only works on domestic flights but the airline will not lose your luggage if they know they are dealing with a legally declared gun. If they do, they get sued by the ATF. Your luggage will be given first priority if you just throw a shitty cheap gun from Walmart in there.
You don't even need to own an operating firearm - if you can get a flaregun, those can work as well. They've got the same travel restrictions, even if they're not as restricted on an ownership level.