Maybe a trifle late, but the most experienced boar hunters I know use either a Smith & Wesson Model 629 in .44 Magnum, or a 12 ga. with slugs.
The handgunner, incidentally, has taken boar in every state where they are found, even has the head of a boar engraved on the side of the Smith's frame. He uses a hard cast 220 gr. flat nosed SWC ahead of a hefty charge of #2400.
My brother had relatives in East Tennessee who had wild boar and black eyed peas every New Year's day. The 12 ga. was their choice.
Never hunted the things myself, but heard many hunters also swear by the Winchester or Marlin lever action in .30-30, used for black bear, too.