I'm about to try something with my Lee 6 cavity 429-200-rf. It gives me bullets with a dia. of .425 along the mold part line and up to .435 across. I really would like it to drop a nice .431, but I will take a nice .430. I'm under the impression that beagling the mold would only be helpful if the part line was closer to spec. I'm worried I'll just make the bullet even more egg shaped if I use the tape method. I thought about sending the mold back, but I'm worried I'll just trade one problem for another by doing so.
I've got a tube of valve grind compound. If the weather cooperates, I'll try lapping this mold on Wednesday. This seems like the logical step, but I may be wrong. I've read up on the Leementing articles and feel like I've got a pretty good idea of what has to go on. My plan,
1. Get mold/alloy to temp by casting until I get nice bullets
2. Lay my hex nuts over each cavity (without the spruce closed)
3. Pour my alloy
4. While the alloy is cooling, probably engrave 1,2,3 and so on on top of each bullet spruce before opening the mold (quickly)
5. Open mold and drop casting into water.
6. Coat the lands in the cavities with compound
7. Install one bullet, rotate with wrench until it rotates with very little resistance.
8. Complete the rest of the cavities in the same manner
9. Begin casting and measure new bullets.
Sound like a good plan?