Can you kill a hog with a .22lr? Yes, under ideal conditions.

Would I hunt hogs with one? Not a chance. If you are very close and get a very good shot at the side of the head, it will get the job done. If a large hog is facing you, a .22lr will not reliably penetrate the front of the skull, even at close range. I've run onto unhappy hogs twice checking traps, where all I had was the .22lr I was dispatching the coons with. The .22lr shots did not penetrate the skull, even at less than 15 yards. These were sows, but not large. The bullets hit the skull and deflected harmlessly upward along the skull. One I climbed a tree and killed shooting down behind the skull into the neck, the other turned and ran before she got to me. Otherwise, I would have been in a mess.