I went to Texas with some local folks hog "hunting". They used dogs to chase them down and we handcuffed them and put a pole through the handcuffed legs and carried them back to the truck alive. We then sold them to game farms that wanted them.
One of the guys also used two rifles on far away pigs....one a .243 and one a .300 Magnum. Long range was important to that hunt when we didn't want to let the dogs out.
From that experience I'd say the ideal hog gun might be a .270 Winchester.....not for the power....but for the range.
BTW....they make excellent breakfast sausage!