Though i've only killed two, both with my blacktail rifle, my buds have killed hundreds and one who was the pig man on Catalena Island for ten years, killed thousands. I like the 25-06 idea, used one on one of my kills at two hundred yds, stoned him. I also have a gun that i've long thought would be excellent in close cover, a model 94 Big Bore Winchester in .375
One of my hunting pards came across a particularly nasty old boar that charged him on sight. My bud shot him with his bow while keeping a brush surrounded tree between himself and the monster. He used up all his arrows yet the pig kept playing ring around the rosie, trying to get at him. Finally, my bud was able to leave, go get more arrows, and come back to a still very much alive and honery pig, to finish the job. They can be very agressive and tough to kill. Know this; They/some will Kill & Eat You if given the chance!