Use anything you would use to kill a deer other than buckshot. The have a breastplate that is really strong so shoot the vitals just above center or put one right behind the ear. They will scream when you shoot them which may bring others in to "help." Be aware of what is going on after you shoot one. They don't see very well, but the can hear and smell very well. If you play the wind right and move slowly you can stalk very close to them or walk up on them by "accident." They move fast and can swim well. They don't turn well, sidestep if one rushes you. Don't believe what you see on Hogs Gone Wild. They are just pigs, they can be dangerous but they will mostly run like idiots when they know you are there. They tend to stay in groups and will scatter in all directions. Be ready for a follow-up shot on a 2nd pig.
Almost forgot, if you shoot a boar...cut his jewels off immediately. They release a hormone or something that will taint the meat. They are good eating, a bit tough to skin. I'd rather eat wild pig than deer.
South Carolina Low Country