I have been casting since the sixties...this is not my first rodeo. I have used several Lee six-cavity molds over the years. Recently I order two 356-125-2R molds. When they arrived, with the sprue plate swung aside, molds closed and held up to the light, I could see light passing between the mold halves. Thinking that the aluminum molds may close the gap when heated, I proceeded to cast bullets with them. What I am finding is that one of the cavities (not all) in each mold produces bullets with slight "fins" (flash), bad enough for me to reject the bullets. Has anyone else experianced the same with new Lee molds?
Note: I smoke the molds with a candle and preheat them by laying them with their bottoms flat on a hotplate.https://pix.sfly.com/im3VoK