RE: Energy vs. Velocity vs. Caliber
Its fun to compare and study balistics but if you figure on shooting game at 500 yards then you better go with at least the 30-378 Weatherby and then you better like recoil. I don't know what you plan to hunt with the rifle but if its deer ,elk moose and black bear then you mention of the 270 WSM would be a good choice. IMO.