We all know heavy and fast bullets resist outside forces the most but we can't have it all and we're shooting projectiles, not lasers. So when does the time of flight become a hinderance to heavier projectiles? Of course this will vary gun to gun but surly we can get it down to a generalization of calibers. Is it better to push a 210gr 2400fps or a 168gr at 2700fps? Where is optimum performance found?