A typical hogs brain is the size of a walnut,good luck with hitting it at 100yrds. If he is close draw am imaginary line from left ear to right eye then right ear to left eye and where these lines would intersect thats his brain. I have had to put down several old boars and brood sows on a farm and found this to be the quickest kill shot. At very short ranges a 17hmr with hornady Vmax would be a safe bet. At any distance over 50yrds I agree with the rest a neck or double lung is best.