ORIGINAL: falcon

"I thought over expansion lead to fragmentation, which limited penetration and then was more likely to wounded an animal."

Not necessarily, especially ifit fragments inside the body cavity.

No, sorry, you are dead wrong here. There is no such thing as "hydrostatic shock" and the deer doesn't die because it's blood pressure goes up, it dies because its blood pressure goes DOWN, all the way to zero. I speak with the authority of 22 years' experience as an animal anatomist, physiologist, and pathologist, 30 years' plus experience as a hunter, and having seen more than my share of gunshot wounds in humans and animals.
You are under a total misapprehension as to the killing mechanism of the bullet -- regardless of type or make. I am not willing to start this thread going on rec.hunting again, but I assure you that there is not, and cannot be, any such effect as you describe as an "instant stroke" from a gunshot wound. Stroke is a much, much different phenomenon and it does not, period, arise from an increase in blood pressure at all. Nor could any such pressure be set up in the circulatory system of any mammal by any bullet under any circumstances

It is often claimed by hunters that as the striking velocity of the bullet increases beyond about 700 m/s (2,300 fps), so hydrostatic shock begins to appear, with the effect that animals drop dead much more dramatically than if hit in the same place with a low-velocity bullet. However, this effect does not seem to be replicated in people; there are many cases of soldiers continuing to fight for some time despite receiving severe (and ultimately fatal) wounds from high-velocity rifle bullets. Furthermore, serious shock effects are only likely if the bullet exceeds the speed of sound in flesh, which is around 1,500 m/s (4,900 fps), but even this has been disputed.

Likewise, some of the inflated prose written by the ultra-high velocity boys makes me want to snap my lunch. To the true believer a bullet traveling over 3000 fps when it hits the target kills like electrocution. The animal just stiffens and dies on the spot, his entire circulatory system blown by "hydrostatic shock." Bullet placement doesn't seem to make much difference, anywhere in the body will do. Intentionally gut shot deer die quicker than those shot squarely through the lungs with a standard velocity caliber. (These guys never accidentally put a bullet too far back, of course.) I wonder how many people believe this stuff, and how many deer run off to die a miserable death because of it?
Both the high velocity guys and the big bullet boys write that their favorites will stop a deer (or some other game animal) when the bullet isn't properly placed. That line of reasoning goes something like this: "Let's face it, not all bullets hit exactly where we aim them, and in those cases the ___ will anchor the animal where a lessor caliber will let him escape."
The only problem is that one "expert" is arguing that it takes something like a .257 Weatherby to perform this miracle, and the other "expert" is claiming that it takes at least a heavy medium bore bullet over .33 caliber to accomplish the same miracle. These are mutually exclusive claims.
I will tell you what I think. Disruption of vital functions kills animals. Massive destruction of organ tissue immediately necessary for life kills quickly. With any reasonable deer rifle caliber from .24 to .45, good bullet placement is what kills deer. If an adequate bullet that expands properly penetrates deep into where an animal lives he will stop living. If you shoot him in the guts, or the ham, or break a leg you are liable to have a problem regardless of the caliber with which you wound him. A good shot with a .30-30 will run up a long string of one shot kills, hardly ever requiring a finishing shot. A careless shooter with a .257 Weatherby or a .45-70 (both fine calibers, you understand) will litter the woods with wounded animals that are never recovered.

ORIGINAL: Todd1700

Chuck Hawks on the subject.