When I say "pig," I'm not talking about Charlotte's Web ones with pink skin and curly tails. I'm talking 100-400lb feral pigs with huge pointy tusks that can disembowel you and your dogs in under 10 seconds. Doing it with a pistol or bow & arrow is harrowing at times as those things usually have no fear of humans.

.44 magnum = scary, close-range stuff, especially if you're wearing earplugs to keep you from going deaf from the blast.
compound bow = not bad unless they run right for you after you shoot (because they didn't hear the relatively quiet arrow shot)
12-gauge shotgun with slugs = good, though it does tend to tear up the meat a bit (side shots to the ribcage or head shots are preferred)
.375 H&H Mag or larger with solids = best; can shoot 'em from almost any angle and kill 'em pretty quickly.