Ok I have just about adjusted everything I can been using mecs for years , mec 9000 loading 20AA compression hulls. Using 20/28 powder throwing 16g, 7/8 ounce loads, bar is throwing 389grs using cb 1078-20 wads. Win029 primers. Here is a picture what is going on I have never had this problem thanks. Ps doesn't do it on all hulls maybe half of them.