I used to guide at a high fece hog ranch here in Oklahoma, and watched hundreds of bow/gun kills. You actually want to shoot a hog big or small in the same spot, take the front leg and belly line, go straight up the leg 2 to 3 inches above the belly line or chest line sounds better. Don't worry about the bone if your close enough to kill it, it wont be a problem, Its actually pretty easy to break. Hogs vitals are in their chest cavity not behind the shoulders like most people think. The mid line of a hog is where the shield is the thickest, this is why most people say their bullets or arrows didn't pass though. 2 to 3 inches above the chest line there usually is not shield, if there is its really thin. I watch hunters shoot 2-300 pounders behind the shoulders and no blood came out because the shield seals right back up, they thought they missed but they didn't. Shoot em straight up that leg 2-3 inches up and any pig will die 99% of the time.