I found that if you head spacing is a little long with the WSM stuff you can set your shoulder back to fit the chamber but the case needs to go deeper to get the area ahead of the web sized back down to fit the diameter of the chamber, but to do that you end up setting your shoulder way back again and the cycle goes round.
I had to grind a die of also but it was to get the brass sized down not set the shoulder back. I reset my head spacing and I can set it up normal now and only bump the shoulder. Grind your shell holder if you need to that's easier to replace.