I have several resizers, one is an old Nygord from years past and I just bought three from a guy in the UK. In my research, I've found that the pellet skirts are normally 0.010 inch larger in diameter than the heads. Makes sense because the skirt will be forced into the leade and will conform the the barrel. I've run a number of pellets through all my sizer. The sizers, of course are incapable of sizing just the head and not the skirt. They both come out the same. With a smaller skirt, there is more energy expended in obturation of the pellet skirt during the shot cycle. Accuracy improvements with sized pellets are just not there. I get better results sorting by head size and weight. What is your experience??