Just to see what it would look like I tried running a 357 mag case into the 300 whisper die. Same body, rimmed, with a somewhat shorter neck. Hey, this thing looks like it'll work! And a whisper reamer with a shoter neck wouldn't be all that big a deal to get made. What a neat Contender or Martini cartridge, or possibly rechamber a 30 carbine Blackhawk? Hmmm......