Your last comment on fat plugging up the hole is why you should be shooting them in the head!
Yeah, well; i like to shoot hogs in the ear. Like i did this 275 pound sow:
http://s290.photobucket.com/user/als...01928.jpg.html
However, in the brush i often hunt you can't always see the ear. Most of my hogs since last fall were killed using a conventional muzzleloader with iron sights. Shooting hogs in the head is an iffy proposition. If the brain is not hit the hog runs off to suffer and die.