Howdy, I know this must be an easy one for some of y'all so that's what I'll ask here!
Today I was casting some pistol boolits with my scrap lead. Mostly WW with a little tin added. 20lb pot heated to 750+/- degrees. I was using a lee 158gr DC mold (357) and a lee 175gr DC mold (40). Both molds were cleaned prior to use with carb cleaner & a toothbrush to remove any oil residue, etc. During my casting after the first few throws the 158gr would have sharp edges 80% of the time and the 175gr would have sharp edges 40% of the time. When I opened the molds before dropping the boolits I could see the molds were not entirely filled when round edges were present.
Why does this occur and how I could I stop it? Thank you!