The problem is I cannot refixture a well used mold accurately enough to remove only a few thousandths.
The simplest fix is to tap the seam where the blocks close at each end, using the round end on a small ball peen hammer. Go gently with this, as the object is to upset the metal enough to make the blocks hold open the .001 or .002 you need. If you get a bit too much, wipe the bumps down with an 8 or 10 inch mill bastard file laid flat on the block faces. It will take a bit of trial and error, but you won't hurt the mold and the bullets will measure almost perfectly round. I could do this for you, but you can do it as well and have it in a few minutes.
Another method which I described somewhere in this forum, I believe, is to glue heavy duty kitchen foil on one block face, a narrow strip vertically at each end. Stick it on with high temperature silicone, which is available from auto parts houses. If you used this method, go very lightly with the silicone and squeeze the blocks together lightly in a well padded vise or with a C clamp till the silicone hardens, which is about 24 hours. This advise is good for any brand of mold except Lee.