My .02 worth is this........if you are a police sniper and expect incredible accuracy, trying to scrimp and save by doubling up on powders is the last thing you should do. Test, test, and retest the top 3 or so powders listed by the manufacturer of the bullets you are shooting. (In my Nosler book only one powder was recommended for both and that was IMR 4350 and like Bigcountry said velocity will suffer) I reload for both of the calibers you mentioned but I use Nosler bullets. I use IMR 4350 for my 06 and H-1000 for my 300 RUM. Bigcountry and Stubble are the guys to ask about Barnes bullets though. Good luck and no your question was not stupid!!