I have been thinking quite a bit about this recently. Most of what I read in magazines/forums when it comes to the effectiveness of a given round boils down to
1. How far a given round tends to penetrate
2. How far a given round tends to penetrate after passing through a barrier like a car door or auto glass
Kinetic energy, velocity, bullet weight and to a extent bullet diameter come into play but generally regarding penetration characteristics. That brings us to the actual shot "stopping" the attack. This is generally brought about by
1. Disrupting the CNS (fastest)
2. Taking out a major organ like the heart (possibly fast but depends location)
3. Attacker bleeds out (probably slow)
4. Pain compliance (arg arg I've been shot)
5. Scaring the attacker away (****! I'm outa here!)
Option 1, 2 and 4 may or may not depend on bullet penetration. I have seen a lot of talk about how bullet penetrates after passing through the previously mentioned auto glass or a car door or heavy clothing and even drywall or a cinder block. My question is this. Isn't a given rounds ability to penetrate bone equally as important?
Options 1 and 2 - I don't work in the medical field but it seems like most of the vital organs in our body are inside of the rib cage. While the rib cage isn't solid there is a somewhat decent chance that a front shot or a side should might strike a rib or sternum. It seems like a rounds ability to break bone and continue on it's path would be a important characteristic. I realize that the angle of a shot play's a role in whether a bullet is deflected or penetrates the bone which brings me to part of the main question. Do certain rounds have a higher chance of breaking bone then other rounds when those rounds are shot at the same angle? IE Is a 9mm ( or insert whatever caliber you like) more likely to be deflected then a .45 (insert whatever caliber you like) if fired at the same angle and it strikes the same bone?
Option 4 - Not so much pain compliance (even though I am pretty sure having a bone shattered is quite painful) but I'm more interested in debilitating mechanical effects of a shattered shoulder, femur, knee, etc. I have no scientific data to back this up but it stands to reason that a attacker with a shattered knee is going to find it quite a bit more difficult to catch me then one with a intact knee. A attacker with a shattered collar bone is going to find it more difficult to stab/wrestle with me. Not because of pain but because of the mechanics of their body not working properly. While not the most effective way to stop a attacker it does seem worth mentioning.
I guess what I am getting at is that a given rounds likely hood to penetrate bone seems to not be discussed nearly as much as a given rounds ability to penetrate auto glass or a car door. I understand that those are important factors for a LEO but as a armed civilian the likely hood that my bullet will strike bone in a defensive shooting seems more likely then a car door or windshield. Is there data floating around out there about ABC round VS bone? Is a rounds ability to penetrate bone something you even think is important? What characteristics make a round good at penetrating bone?