I've about decided that the most reliable way to take hog is to put a single round into the ear. I've seen a 250-300 lb sow keep on chugging after being hit with a 165g '06 to the rear of the lungs.
But all seem to fall to a shot to the ear. I know two guys whose favorite hog rounds are .22-.250, employed in this way.
Last hog I saw taken, though, (last week) was a 200 lb sow to a blast of 3" magnum 12 ga. 000 buckshot to the midsection. (There were a couple of pass-throughs, to my surprise.)
I would personally consider a .308 to be plenty for any hog.