In my experiences in the field, I have always done my best to get, in my minds eye, the optimum shots on game. To me, whether it be deer, hogs, or whatever, I have found that if I could get a shot through, from one of three angles, the animals generaly hit the ground asap. I concentrate on the shot, similar to the way a boxer throws a punch, I strive to visualize the opposite side of my target. This is a crude diagram, but it shows what I am referring to,
It doesn't have to be exactly as shown but in the genral areas, so to speak. This generally at least insures that vital life giving organs are disrupted, and the central nervous system receives a pretty good shock as well.
I have however, seen my dad, put a 150gr Sierra through all three of these directions on the same deer, with no visual indications of a hit at all. The deer was only about 40 yds away and just kept his stride walking across the top of a small hill. After waiting a while, he decided to head to the house figureing his scope "HAD" to be off, he walked over the top of the hill and there laid the deer. Worst part was while dressing it out, he slipped and dang near cut a finger off, which left me to do the cleaning of his messed up deer. I told him that was a little extreme, just to get out of cleaning up a mess like that. Believe me it was a mess.:p
I realize that other game might be tougher or more reselient to shock or trauma than others. Hogs are a great example. If you shoot a hog behind the shoulder, you just about miss all of the lungs and the heart by a decent margin, and generally get mostly paunch. Their heart and lungs are tucked up in the front part of their body and you just about have to aim for the front point of the shoulder to hit it. This is why they seem to be so tough to the shots taken on them. Check out the below link, it shows their internals up close and personal.
Hunters Anatomy of a Hog
Also if your interested in hunting hogs, that is a terrific site for info on various ways to attract and hunt them.
Maybe sometime, someone out west might be able to put something like hat together showing the vitals on an elk, in relation to the exterior hide and such. I know it might help out a few hunters who have never been able to hunt them yet.