I have a Lyman single cavity mold for the 45 acp that I inherited from a very dear friend years ago. It's not fast, but it DOES cast a nice boolit. Problem: one cavity will not let the boolit drop. Okay, so after lapping the cavity (twice), smoking, etc. I finally discovered that the sprue plate is not sliding across both tops evenly, resulting in a microscopic "flashing" on one block so it requires a lot of tapping to release. Not good, and very slow production. A replacement sprue plate was tried, with exactly the same results.
I should have spotted this immediately before doing any lapping, as the rub marks are pretty self explanatory. It's okay though as the cavity is nice and clean now, without being enlarged. But I still have the problem of one block being about .001-.002" higher, causing the sticking.
Is there anyone out there that can remove the sprue plate stop pin, surface grind the tops even, reinstall the plate and pour a few test casts to see if there's any improvement?