I recently picked up a lee 7/8oz slug mould to play with. It came with loading instructions for very specific loads. I am happy with about 1250-1300fps as I won't use these for anything but making a bang. My question is can I just drop in one of these lee drive key slugs on top of my standard trap and skeet loads? 7/8 oz of shot is the same weight as 7/8oz of slug right? Would the pressures spike or would it come out just like a load of #8s?