Paul, I think you really explained it well. I think "hydologic shock" is a realistic term. Tissue damage is a factor in rifle kills as well as hemmorage. This year I shot a ~120 lb live weight deer broadside with my .308, 150 gr core locat 20 yards. I hit it squarely behind the shoulder, it collapsed but regained its feet and made a strong 50 yard dash. A friend of mine shot a very large doe with a .300 win mag, 150 grain bullet, broadside, 20 yards, same shot placement, it reacted exactly the same. No exit wound with the .300, yes exit wound with .308. Lotta variables, but knockdown power is not one of them.