Interesting. I've always considered from the standpoint of gains in yards, so to speak. I.E. what a 270 is doing at say 300 yards, a 7 is going to do at "X+125yards" or whatever. If drift is the biggest concern (and should be) then shoot no further than where your ability is to that regard. If 14" is manageable, then .625 BC is it at 500.
But, this thread will die and in six months start all over again with the same answers.
