w good friend was loading up some 50's and got one stuck in the sizer. he ended up having to cut the head off the case and driving a wedge between the die and the remaining case to collapse the case. anyway he had a couple small scratches on the die afterwards. So he took a wood dowel (3/4") cut a slot in it and wrapped some 400 grit cloth around it. chucked in the lathe the end result was a really high polish on the inside of the die, with a minimum of material removal.and now the sizing operation yields much less effort.
i tried doing the same thing only using 800 grit. there wasn't a measurable amount of material removed die now has a mirror like finish and sizing effort is noticeably reduced