bigcim,
You can adjust the sizing by milling off a few thousandths from the shellholder, which will allow the case to go that much further into the die. I've done this with other calibers and it's worked fine. As mentioned above, if the size die doesn't reduce the case enough for your chamber, then another die is called for.
With belted cases, you can't force the case into the die past the belt, but if the shellholder is too thick, and some are, then taking a little off the top will sometimes cure the problem. Shellholders are hardened, so you can't use a file on them. All you'll do is dull the file. I usually use my drill press and a rotary grinding wheel in an arbor and use the traveling drill press vise as a milling machine.
I don't recommend grinding the die at all, since shell holders are cheap and dies aren't.
Hope this helps.
Fred