This reply is a bit late, but I just got a micrometer top compression die this week. It came from
www.gmwvickerman.com It is not in their catalog yet and you will have to ask for it.
Actually I should back up a little. I ordered a 45-70 Vickerman inline micrometer top bullet seating die and then asked for a micrometer top compression plug to go in it. It came as a set.
The Vickerman compression die with the sliding sleeve and mic top have made loading better and easier. You can dial in the amount of change you need when compressing. The compression plug is held inline with the case so no more "edge bites" on the cases.
Doz