Is there any where you can find info for bullet weight / powder combo for barrel lenght? For instance: I have a 308 win with 22 inch barrel and want to shoot 168 grain bullets, lets say Barnes, Will IMR 4064 perform better than 4320 or 3031 for this combo? Heck Barnes shows 12 different powders for the bullet weight. Or is there a rule of thumb to go by. Short barrel faster powder for heavier bullets? or the opposite? slow powder for heavy bullet in short barrel ?