Are you considering 2.75 or 2.5"? Go to Alliant's reloading center for tested recipes for Cheddite hulls and Cheddite Primers. Alliant has recipes for 2.75" using RD and AS. Hodgdon's reloading center has a recipe for 2.5" using the Cheddite hull and primer using Universal. BP has a book dedicated to Cheddite hulls and primers. You have a motherload of primed hulls which most likely are primed by Cheddite. Good luck. Gil