I am sure that I am doing something wrong. I am seating cores in 6mm rebates boat tail dies and on the upstroke the cores are jumping up in the jacket. Sometimes the core comes all the way to the top of the jacket. Seems to happen more often with soft lead versus a small amount of alloy.
Cores are cleaned with brake cleaner and the Coleman fuel before drying for at least a day.
Any thoughts are welcome. Thanks.