For me, it has to be auto cartridges chambered in revolvers. I mean, really? Is the evolution of the revolver and their cartridges over the past 100 years not perfected enough for you? I've never held a revolver in, say, .38 Special, and thought "yes, I wish I had this in......9mm Auto!" That's just really stupid. What can't I do with a hot-loaded .38 that I can do with a 9mm? Or even a .357 Magnum? That being said.....I certainly wouldn't say "no" to a Charter Arms Pit Bull in .45 ACP if it landed on my doorstep. To me, that's a modern interpretation of the old .45 Colt of yesteryear. And I like that. But all the rest of it is just stupid. 10mm Auto in a revolver? I love Rugers, but that's just a really stupid idea. Be a man....get a .41 Magnum. So what about you? What is your pet peeve when it comes to firearms?