The best target area is the head. There isn't much neck, and everything else is either meat or guts--which ain't where you want to hit.
First thing, cut out the scent gland that's in the skin on the pig's back. With a head shot, you can gut one out without even getting your hands bloody. Greasy, yeah, but not bloody.
The hide is tough and the hair is dusty, so a knife will dull down sorta fast, compared to Bambi.
If you see Piggy at a distance, it's easy enough to walk up to within close range. They're very nearsighted, and don't hear nearly as well as deer. If you work the wind, you can get close enough to grab a baby, just for the giggles. The younguns are fairly easy to raise; they're territorial and make great watch-pigs.
The best gun, really, is whatever pistol with which you can hit most accurately. .38 Special on up. No point in shooting from a distance; ya gotta walk up there to gut him, anyway.