Ok guys, I've read two reloading books. Picked up some RCBS Carb dies for two different loads I want to load (9mm & .40 SW) Ill slowly get the components needed to start reloading. A couple of questions come to mind right off.... The books state "not" to substitute ingredients (case, primer, powder, & bullet). Example 9mm Luger: .....Case Federal .....Primer CCI 500 .....Primer size Small pistol .....Powder XXXXX So if I cannot find a specific primer brand or case brand I cant use another brand? What if I dont have Federal cases .I may have Winchester, Magtech, Remington is it a big difference if I use a different case for reloading? From my reading it appears it is very important to match bullet weight to powder load that much I understand. I get the point that I need to use suggested powder grains and not to exceed Max load grains. Second major question. I picked up a 3 die sets yesterday for my 9mm and .40SW. Dont really understand yet what each does (in the loading process) and there wasnt any real explanation in the directions maybe Im getting old! I imagine Ill learn as I keep reading but will I need any addl dies for reloading? At the store I saw boxes marked Group A and Group B. The salesmen couldnt answer my questions .so whats the diffence? Thanks guys .hate to keep asking .but I want to learn the right and safe way of reloading.