Did you weigh that hog, and was it killed in Penn? My son said they got their hogs ( the game ranch) mostly from Texas, which is where I live. I have friends that trap'em and sell'em to the hunting ranches. They castrate them before re-releasing them, and I think that's why their looks change, and they get so big.
I have killed some weight close to 400lbs, but usually a 350lb is a very big hog. They only live to about 6 years old in the wild. They wear their molars down foraging, and more or less starve to death I guess. Anyway they get weak, and if coyotes don't get them then, they just die. Of course other hogs may eat them, a hog will eat any thing, including you, if he gets a chance. They aren't as hard to kill as people think, but I don't hunt'em with a 22lr.
I have shot them with everything from a 4570, which is more than enough, to a 223 which if your a good shot is plenty. My favorite is a 3030 or 357 mag in a Model 92 Winchester rifle. Either will handle a big hog.
I'm guessin your hog is pushin 600lbs. Is that close?
The hog I am kneeled over in my avatar goes about 300lbs and is a black boar,(I'm a pretty good sized guy) and as you can see I am holding the M4 I shot him with. I eased up on him while he was sleepin under a cedar tree, in a cedar break. I'm a sneaky kinda guy that way. One shot to the neck, and he never got up. Used a 52 grain match hollow point. Drug him out into a field with a jeep.