I agree on the rifle where practical--in fact, I bought a .45-70 specifically for hogs. Nothin' says lovin' like 300 grains of solid copper at 2000 FPS. I saw the OP's comment about "walking up on" a hog, though, and read it as him being less concerned when he's on the tractor and more when he's out walking his land. A rifle would definitely be better, but may not be practical for dismounted carry. As to caliber, .357 Magnum is the bare minimum with which I'd be comfortable, and then only with hard-cast loads. .45 ACP (my round of choice for social work and target shooting) is right out--I'm just not sure it'll penetrate the shield, and anything from the front is liable to slide right up the skull, given the angles. .44 Magnum is perfect here.
I definitely agree about the training and practice. I've been to a couple of shooting schools, and I am amazed at how perishable pistol skills are, especially against moving targets. Somehow, rifle skills seem to stick around a lot longer.
