If you've flown with handguns lately you know most of the drill. Sounds like you are primarily concerned with theft. As in, "Dude! Look! There's a gun case on that carousel! Let's get it!" The protocol should be that a large, recognizable gun case goes to the luggage office and not onto the carousel. I'd try to make sure that's the case. Poke the people when you check in to make sure.