The last time I checked, feral swine have not been cross breeding with cape buffalo or elephants, thus they can be killed.
My hog trapper has has taken one hog which weighted 300 and one at 350, his largest to date since he started trapping. Very few feral hogs in the wild will weigh over 225 or so.
If you are paying to hunt hogs 300 lbs. and over, they have been fed and are stocked for hunting for the most part.
The majority of the hogs I kill, are shot with a .222 when free ranging, in the trap it's rim fire. Study hog anatomy and you will find they are built different than a deer, shoot further forward.
Dah shield, there is a group where I live whom hunt hogs with dogs and kill them with knives. How can a knife penetrate the shield and not a round ball. Oh, if you castrate a male hog the shield will dissolve after castration.
My hog trapper told me how many piglets he catches in his traps and how they squeal when he loads them up. He said only once has he been challenged by a female hog.
Anything that will kill a white tail deer will take care of a hog.