4seventy:
Your resizing problem may be related to an incorrect shell-holder, rather than the die. Is the shell-holder the same brand as the FLS die? In a non-standard size like .470, there is likely to be quite a bit of variation. A die-maker can only judge the full-length dimensions against his own shell-holder.

I would NEVER grind down a die worth maybe a couple hundred bucks, when you can face off a shell-holder worth maybe 15 bucks for the same result!!