A hog is not built like a deer. A hogs heart and lungs sit very low in the body. For a hog that is broadside a bullet in the ear, below the ear or on line between the ear and will do the trick every time. A shot low and just behind the crook in the front leg will also do it every time.

http://www.hunting-in-texas.com/learnhogs.htm

Most of my hogs have fallen to a .50 inline muzzleloder. A few dozen of them have been killed with a .22 magnum and a .223.

Shooting a big boar hog in the shoulder is not the answer unless you are using heavy for caliber bullets that will hold together well.