Originally Posted by drockw

You're arguing a completely different point. I'm noting that it is absurd to say that because a bullet entered at 2500 ft lbs and exited at 2000 ft lbs, that it "only expended 500 ft lbs as it traveled through the deer." That's pure unadulterated BS. It has lost 500 ft lbs on its way through, but, it is expending energy during every microsecond of its travel through the deer. It's simply ridiculous to say that a deer hit in the front should by 2500 ft lbs, and in the rear shoulder by 2000 ft lbs has had less energy "expended in the deer" than one that gets hit in the front shoulder by 2500 ft lbs and 0 ft lbs in the rear shoulder because the bullet "expended all its energy inside the animal" and didn't fully penetrate. A hunting bullet that fully penetrates, and carries its KE all the way through the deer is going to cause more permanent and temporary cavitation on its way through than a bullet that stops half way through. Your apples to oranges comparison using the FMJ bullet kind of proves the point that its not the KE that kills, since the FMJ has the same amount of KE as the soft point. What kills is the damage caused on the way through, which is the result of the interaction between the bullet and the tissue. Try carrying your hypothesis in the other direction, using a 100 gr bullet of light construction designed for varmints, versus a 100 grain bullet designed for deer that fully penetrates. Both enter with the same KE. The varmint bullet expends all of its energy, but, doesn't penetrate very far. The bullet designed for deer holds together and fully penetrates, causing damage all the way through the deer. Which would you rather have?

Once again, the idea of "transferring all the energy inside the deer" i.e. by not fully penetrating, is ridiculous. There is far more energy transferred during a full penetration event.