Back to the OP, and notwithstanding what BRL has posted, I have shot and killed DRT a LOT of hogs, under ideal conditions, over corn, with a very accurate, scoped, 22LR rifle from an elevated steady rest, under 25 yards, in the forehead "X" between the ears and eyes (where the skull is thin and the brain is just underneath). A "whap" right there and it is OUT GOES THE LIGHTS. Same thing for a side shot to that portion of the head - above the upper jaw, behind the eye, all the way back to the shoulder, but not with the 22LR, as the side skull bone/hide is too thick.
I am working on a 180 grain (heavy for caliber), cast, gas checked and lubed, 38 Special case (small capacity), IMR 700X (small charge of fast powder), for my Handi-rifle in 357 Mag caliber and an extended range, not to exceed 100 yds (maybe 50 with the 38 Spc case). I know, without the empirical evidence, that the 357 has MORE POWER, GREATER PUNCH, and the potential for equivalent accuracy as the bolt-action Ruger K77/22RP that I now shoot.
Try NOT to take an off-hand shot as there usually are more suitable and stable alternatives. Hog hunting is somewhat forgiving in that their eye sight is poor so you can move around a little bit. Sometimes even to within a few YARDS of them as they feed, provided you are quiet while doing it. They make a lot of noise themselves.
Your current participation in practicing with your gun does a favorable service to your adversary. I am certain that you will succeed in your hog hunt with the 357 Mag, provided you do your part.