I end up with a rough finish on my cast pistol bullet bases from time to time. I don't discover the problem until I have a whole pile of them. It causes them to not sit flat in the die and may cause an alignment issue. Ive heard of H and I dies that had a recess in the 'I' die. I'd like to do this to my .452 and .358 dies. I have a minilathe and minimill. Are these dies hard enough to need a carbide endmill, either plunged with the mill or held in the tailstock? Maybe trepanning in the lathe?
Any thoughts?