"You have any .45 Long Colt, .410, or .454 Casull?"
"We do have some .454."
"Oh, good, I need some ammo for my Judge."
"Ah, wait a minute.."
Took some talking to(I think) convince him that just because he read somewhere that you can load it with that doesn't mean it's true. Or a good idea. Pointing out that his was specifically marked for .45 Colt or .410 and said NOTHING about .454 Casull didn't seem to do it. Finally saying "If you do that it'll probably blow it up in your hand" did seem to make an impression.
I checked, and Taurus does indeed now make a Raging Judge that'll handle .454; here's hoping that nobody plays "If it works in that one, it should work in mine!" and loses a hand(eye, face, whatever).