OK. It's important in reloading to use all the same brand cases when working up a load. Total uniformity is a big key with it.....everything the same all the time.....cases, bullet producer and weight, primer, powder manufacturer, etc.... You can change a component anytime you wish, but there is a good chance it's going to change the charactaristics of the load. You gotta stay uniform thru the development stage. Hang in there, zrex... ....