I'm about to start my 3rd hog hunting season. In my first season, I shot 22 hogs on private land with corn and game camera. Any .223 or greater shot to the ear will drop a hog instantly without spoiling the meat with adrenalin. I've personally seen a .270 ricochet off of a head-on shot (my boy shot him between the eyes and we both saw the bullet ricochet off). If the hog is looking at you, forehead shots sometimes hit their plate armor, sometimes drop them. Head-on eye socket shots are like profile ear canal shots... excellent with any caliber but you only have 1/2" margin of error. Largest hog was 500#. I learned all that my first season.
My 2nd season was on WMA land as the private land I previously hunted on was sold. It took me 6 weeks to locate the hogs in quantity, so I only took 10 hogs last season. Most WMA hunting is with .22 rimfire. I dropped a 55# hog in the head 9 times with a .17... so that was the last time I ever used a .17. You have to use HP rounds with rimfire, preferably high velocity (CCI has some good rounds). I shot many hogs in the head with .22, watched them drop, gathered my gear and made my weapon safe, went to get the hog and he was gone. Probably happened 10-15 times. I was hitting them in the head, profile view, going for ear canal and knocking them out. Their head plate armor is just too strong and margin of error too small for rimfire. Then I started with rimfire neck shots and immediately starting harvesting hogs. My 14 year old son and I walked up to a sleeping hog both carrying .22lr. My son stepped on a twig, another hog we didn't know was there started running, I dropped him with one neck shot then 5 more hogs jumped up and started runnibg. My boy shot once to the neck, dropped a hog. I acquired second target and shot once again to the neck, then the rest of the hogs were gone. 3 hogs in 2 seconds with .22lr neck shots.
The season in LA on WMA land opens this coming weekend and my boys and I are bringing .22lr to the fight, prepped to shoot for the neck. Just got my small caliber suppressor in, so we will start with my Savage .22 bolt action suppressed with subsonic ammo. Hope to quietly harvest squirrels while hogging, and also increase our chances of taking multiple hogs at once with suppressed fire. Hope this helps you.