I guess it's just me, but I'd just loaded the 9mm cylinder with .357s and vice versa and lived happy. But, I was never a perfectionist so long as it worked right. The cylinders on my Ruger convertible aren't even marked. I can just look in a chamber and tell by the depth of the chamber which caliber it is. I'm talented that way. I guess I could mark 'em myself if I weren't lazy.