You can easily make a stuck case remover. All you need is a 1/4X20 tap, the appropriate drill bit, a matching bolt, a couple of 1/4" drive sockets, a washer, and a wrench. Drill and tap the stuck case (after you remove the decapping stem), then put the bolt through the washer and two sockets (unless you have deep well 1/4" drive socket), making sure that the "open" end of the bottom socket is riding on the rim of the die, not the casing. Then screw the bolt into the threads of the casing. Put the die in a padded vise, then just turn the bolt until the casing is pulled out of the die.