I am brand new to reloading and I'm anxious to get started. I've picked up the RCBS rock chucker supreme kit, a couple pounds of H4350 and Hornady 143 gr eld-x for 6.5 Creedmoor. I have some Sellier and Bellot brass that I want to make use of and reload. I can't seem to figure out how to tell what primers I would need for that brass. I looked on the SB website but didn't find anything definitive. Anyone know if I need Large or Small Rifle primers for that brass? Also I only seem to see Magnum primers available...what is the difference and Standard and Magnum? When would I need Magnum....or not? Thanks!!