Marlin670, your son's shot to me is more impressive of a hog survival story...glancing from the front like that is wild! And he stayed down longer than mine did.
It was a side shot on mine..you could see dust fly in the distance behind the hog . 100% glancing shot although at the time I made the shot I didn't realize this because I was already moving my eyes in the direction of another hog off to my left.
It was almost exactly a year later when I finally (unknowingly at the time) killed him for good. I shot him (along with 4 other hogs that evening) with not a ton of daylight left and I let the buzzards have them...so I didn't pay any attention to areas of them that I didn't hit with a bullet that day...although there wasn't any obvious signs of a previous injury to the head. I would probably have noticed that.
I've actually had 3 hogs run off in this manner...side shot on the head resulting in an immediate drop. When they do there is no blood trail. This one was the only one I got on video, and the only one I actually got to see run off. He's also the only one I know for sure survived long term (since I later killed him and found the healed impact on the skull).
Edit: Figured I owed it to you guys to go dig up the full video and post it up. It shows a better representation of how long the hog was down before he got up and ran off...also there's some pretty crazy pissed off hog sounds in it!
MVI 0905 avi