I've never hunted pigs, but, the impression that I get is.....they are tough little buggers. It seems that they are shot at fairly close range, but you've got to hit them hard. You don't need a long range cartridge or more than a 2.5X scope. A red dot would work well, also.
A lever action in .44 Mag or the traditional .30-30 would be my way to go. I've already got a Winchester 94 .30-30, so thats my choice. Bob