Some thoughts on bullet performance.

Started by gitano, November 09, 2004, 10:15:20 AM

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Many, many times, I have observed bullet performance that was either not what the “experts” swore it was, or even what I thought it might be. In most cases, these surprises were with hollow point bullets. As I have recently begun to use slow, “fat” bullets, I am seeing more surprises in performance. In the end, I have come to the personal conclusion that there’s a lot more to “knockdown power”, or “hammer effect” than can be easily quantified. Furthermore, I am unimpressed with kinetic energy as THE SOLE measure of terminal performance.

I have read several authors that have developed “equations” or formulas to try to quantify the contribution of bullet diameter on terminal performance. Most were either poor results due to the author’s lack of math or physics training, or they were simply self-aggrandizement. The only one I have ever cared much for was Water’s formula, and truthfully, even that one is of marginal value. At least as importantly to me, is the fact that there is no way of quantitatively evaluating the effects of high speed and/or hollow point bullets.

Lest someone jump to a conclusion, I am not about to propose any such equation in this post. I have no great new idea about how to easily quantify the effects of bullet diameter on terminal performance. Nor do I have any such idea about how to easily quantify the effects of fast hollow points. But I do have some opinions on WHY those bullet characteristics are so effective, and I do have an idea about how to test these ideas, albeit neither simply nor inexpensively.

First I want to introduce a new measurement characteristic to the discussion of terminal performance and "lethality"– work: more specifically, work per unit time, AKA power. In classical mechanics, work is defined as force applied over a distance. English system units of work are foot-pounds (don’t confuse with energy – very easily done) metric system is joules. How much work is accomplished per unit time, power, is watts in the metric system. The math and terminology is very confusing in the English system of units, so I am going to stick to doing calculations in the metric system. The ratios would be exactly the same in the English system of units. Also, before you take me to task on terms and units, 1) hear me out, and 2) please only correct my arithmetic errors, or erroneous use of a term.)

Before I get to the description of how to measure the work done and power exerted by a bullet in an animal, let me talk about my ideas regarding what’s going on in the animal as the bullet transfers energy and disrupts tissue. I think most of us will agree that tissue disruption, in all its many forms, will kill the (big game) animal. If we poke a .50 caliber hole through the heart of an elephant, sooner or later, it will bleed to death. What many do not agree on, is the effect of a phenomenon generally referred to as “shock”. “Shock” is a nebulous “force” that is not connected to the direct physical damage that the physical bullet does. It is instead often referred to as hydro-static shock, implying (and often stating outright) that a shock wave created by the bullet compressing body fluids (interstitial fluid and blood), create a physically destructive wave that disrupts tissue or “shocks” (whatever that is) the animal. Others argue that there is a physiological shock to the central nervous system (hereafter CNS) created by the shock wave. The effects of the physical shock wave are easily demonstrated – those of the physiological shock wave to the CNS, are not. Personally I have faith (since I cannot see it, or otherwise empirically demonstrate it), in both phenomena contributing to the “lethality” of a bullet. So, let me put succinct terms to these three components of “lethality”. The hole I will refer to as direct tissue disruption (hereafter DTD), the tissue damage caused by the hydrostatic shock wave I will refer to as cavitation damage (hereafter CD), and the physiological shock to the CNS simply as “shock”. Let me define another term – dead. Doesn’t seem to be too ambiguous, but I want to define it in terms of hunting, not physiology. Therefore, for this discussion, I consider an animal “dead” if it is on the ground and cannot gather its feet underneath it to escape me. If I can walk up on an animal to apply a coup de grace it was “dead” when it fell to the ground.

OK, if I don’t think the bullet’s kinetic energy is the sole explanation of why “fast” bullets, especially HPs seem to “hammer” most critters to the ground, than what is it? In a word – power. The question of lethality is answered in my opinion by how FAST a bullet drops its energy in the animal (power), AND over how much AREA is this force applied (pressure).

Let’s take a big, fat 300-grain, ‘solid’ .458 caliber bullet doing 2000 feet per second (~610 m/s) at IMPACT. (Muzzle velocities are irrelevant.) Its impact energy is 2664 ft-lbs (~1964 J). The frontal area over which that bullet transfers energy to the animal is 0.165 square inches (~106 square mm).

Now let’s take a 225 grain, round-nosed, ‘solid’ .308 caliber bullet doing 2309 f/s (~704 m/s) at impact. Impact energy is the same 2663 ft-lbs (~1964 J). Frontal area over which that bullet transfers energy to the animal is 0.075 square inches (~73 square mm).

Now let’s take a 115-grain hollow point .284 caliber bullet with an impact velocity of 3230 f/s (~985 m/s). Again, the impact energy is the same 2664 ft-lbs (~1964 J). Frontal area is 0.063 square inches (~41 square mm).

Now let’s “shoot” a couple of animals behind the shoulder and between the shoulder blade and the heart, hitting neither the shoulder blade nor the heart, and let me suggest what I think happens up to the point that the bullet stops or exits.

The animal will be a 220-pound (100 kg) whitetail. It is my belief that the .458 will exit the offside (hereafter ‘perforate’) of the deer. Therefore, some unquantifiable amount of its 2663 ft-lbs of energy will be “wasted” on travel past the deer. However, it will make a .458” hole creating a DTD volume of at least ~1.5 cubic inches, (the volume of the tissue disturbed by the bullet assuming it travels through 9” of deer), plus there will be some CD, and probably considerable shock. Unfortunately, we can’t really calculate any numbers other than a conservative wound volume, because the bullet perforates the deer. However, it is well recognized by those that have shot deer with this caliber bullet, that they die (remember the hunting definition) quickly. Whatever proportion of the 2664 ft-lbs of energy was dropped on the deer, was dropped ahead of a half-inch frontal area. We cannot calculate the power (work per unit time) accomplished by the bullet because it perforated the deer. However, if we assume that the bullet traveled trough the deer at impact velocity, it then spent 0.000375 seconds in the deer. If we assume it dropped ½ of its energy in the 9” of deer, then the power exerted was 1964 j divided by 2 (the change in KE is the work) or 982 j. 982 j divided by 0.000375 seconds (the time it takes the bullet to travel the 9 inches), yields 2.619 megawatts – the power needed to cause the bullet to drop ½ of its energy. Or, put another way, the 982 j was the work needed to convert half of the KE to other forms of energy and rend flesh.

Next is the .308 bullet. Same impact energy, but about 300 fps more speed at impact. Being a round-nosed solid, I will say this bullet also perforates the deer. It makes a wound channel with a volume of ~1.0 cubic inches. As a RN solid, the frontal area it has with which to create a shock wave is less than half of what the .458 has. And while we cannot calculate exactly what that value is, we can know that the energy transferred is proportional to the resistance, and the resistance of the .308 is probably about 45% of the resistance of the .458. Furthermore, the .308 will actually spend less time in the deer by virtue of increased impact velocity, and decreased resistance. Therefore, it is a certainty that it will convert less of its 2664 ft-lbs of energy to tissue damage, than the .458 will. Let’s assume some numbers: since the frontal area ratio is 75/165, let’s say that the dropped energy is 45% of the .458’s dropped energy, or 444 j. The bullet stayed in the deer only 0.000322 seconds, therefore, the deer only generated 1.389 megawatts of power in slowing down the bullet as it did.

Now to the .284 HP. It is unlikely that the HP will perforate the deer, and for this discussion we’ll say it doesn’t. At impact, the HP starts to open up, and is fully “mushroomed” within 6 inches of the entrance hole. It stops inside the chest cavity without penetrating the far side of the rib cage. The whole 2664 ft-lbs of kinetic energy are transferred to the deer in the form of DTD, CD and shock. The DTD will be significant, but indeterminate prior to a necropsy. Whatever physical wave was created by the bullet, the frontal diameter would likely have been on the order of 2x the original diameter, or .568”. But to my way of thinking, the most significant point is the TIME over which the energy is dropped. The power required to stop the bullet will be considerably more than the power dissipated in the above bullets. 1964 J/0.000155 seconds equals 12.687 megawatts, or almost 5 times the power needed to slow the .458 down, and 9 times the .30 caliber bullet. I want to stress that these calculations are strictly “seat of the pants” stuff based on reasonable guesses and proportions. While the exact values are most likely wrong, the proportions are probably not far off.

Let’s take those values on their face for the moment, and talk about “toughness” of critters. Personally, I DO think some critters are tougher than others. Also, I think there are two parts to “toughness”. The first is purely physical. Elephant bones are denser (tougher) than most smaller animals because they have to hold up such enormous weight. Whether Cape buffalo bones are tougher than other large ungulates is debatable, but measurable. (However I do not have access to such measurements.) The second part of “toughness” is what I will call “attitude”. Now before someone takes me to task for anthropomorphizing, (ascribing human traits to animals), let me clarify that opinion. Certain animals, especially after they reach sexual maturity, “realize” or have an understanding of their “vulnerability” to predation. Here’s where I would acknowledge the “special” toughness often ascribed to most of Africa’s Big Five – elephant, rhino, Cape buffalo, lion, and instead of leopard, I would substitute hippo. I would add to the African list, eland and giraffe. These animals, especially mature bulls, “know” (have a conscious awareness) that they are basically “beyond” danger from predators. (Size does matter.) As such it doesn’t enter their ‘psyche’ that they are ‘mortal’. Hence when they get shot, they’ve got an “attitude” that may very well sustain them long enough to stomp mud holes in you before the effects of a non-shocking bullet take effect. Hence the need for brain shots in elephants and bone-breaking shots in the others.

Smaller herding herbivores, otherwise known as “food for everybody” never develop this “attitude”, and when shot are just as likely as not to lay down and die or run off, instead of “defending” themselves. While I have not hunted Africa, I have seen this very “attitude” many times in brown bears (”immortal”) vs. caribou (“I’m food”).

Now, “attitude” and actual physical “toughness” aside, in my opinion, there is another factor that plays a very important role in an animal’s ability to withstand “punishment” as gun writers are wont to say. That is sheer mass. Consider the above numbers. Which animal would be more capable of withstanding a 12-megawatt power surge, a 100 kg (220 lb) whitetail, or a 1000 kg (2200 lb buffalo)? We can actually calculate that to a certain degree in the form of watts per kilogram. In the whitetail, the figure is 12.687MW/220kg, which equals 57.668 kW/kg. In the buffalo, the figures are 12.687MW/2200kg, which equals 5.767 kW/kg. What that means is, each kilogram of the buffalo only has to dissipate about 6 kW of power, whereas every kilogram of the whitetail’s flesh has to dissipate 10 times as much, or 60 kW.

The larger the animal, the more flesh it has available to dissipate power. If it has more flesh to dissipate power, the less any one kilogram of “flesh” will have to take. That means that a specific organ, or the CNS will dissipate less power per unit mass in a large animal than it will in a small animal. The less power dissipated per unit mass, the less the damage incurred.

So… not only do very fast bullets cause massive DTD, and CD, they also cause the critter’s body to dissipate a greater quantity of power even if the two bullets are delivering exactly the same kinetic energy. In the case of “big” critters, where their mass is sufficiently large so as to be able to "manage" the power dissipation, only big, fat, deep –penetrating bullets can provide the necessary DTD (especially to skeletal structures) to disable the critter until it “realizes” it is “dead”.

Here’s how these “theories” can be quantitatively tested. A 12”x12”x24” (or any appropriately sized) block of ballistic gelatin is set up at the appropriate distance to permit the desired impact velocity. In the gelatin at specific and uniform distances in 3 dimensions, 3-axis strain gauges are imbedded. Upon bullet impact and transit through the block, the strain gauges will measure not only the pressure, but more importantly, the pressure per unit time. The pressure-time curves, will illustrate clearly the effect of each type of bullet tested. Of course, this would be very labor and instrument intensive. Which translates to expensive. Why would premium bullet manufacturers want to conduct such a test if the results might demonstrate that their “premium” bullets aren’t so “premium” after all?

Be nicer than necessary.

drinksgin (deceased)

Very interesting, as an electrician, I appreciate the idea of Watts as Work. The test setup might give some very interesting results.
I would like to see results on fairly soft bullets at 1400-2000fps as well, especially larger diameters.
NRA life, TSRA life, SAF life, GOA, CCRKBA, DEF -CON

Daryl (deceased)

Good points Paul, and rather than argue with you about any point you've made (I tend to agree with you on what you wrote), I'll only add a few thoughts.
My approach to "killing ability" of a cartridge/bullet combination is fairly simple. Bullets kill, IMO, in a variation/combination of four ways:
1. Central Nervous System damage. This is most often the quickest way to kill an animal, since damaging the central nervous system pretty well shuts down the animal's entire bodily system. No brain, or no nerve impulses sent by the brain, and the animal drops in it's tracks.
2. Blood Pressure Loss. Hit the heart or a major blood vessel and the blood pressure of that animal drops either instantly or very quickly. No blood pressure and the animal drops quickly. This is often seen when the lungs or heart are damaged, and while the animal may run a short distance, it's not going far.
3. Blood Loss. If a MAJOR blood vessel/organ isn't damaged, the animal can still bleed to death. Blood loss will eventually result in blood pressure loss, but the actual blood loss still results in oxygen not being delivered in sufficient amounts to keep vital organs operating properly.
4, Organ damage is the last way that I consider to be death "caused by a bullet". If an organ that is not needed constantly to keep the animal operating is damaged, the animal will still likely die. No stomach, intestines, and so forth, and the animal will invariably die. The death is often complicated by infection (which I don't attribute directly to a bullet's effectiveness), but the result is the same.
Now, not to make light of what Paul said above, but if ANY bullet damages the animal in such a way as to cause the above described trauma, that animal will die.
A fast expanding bullet that reaches the lungs will often drop an animal in it's tracks. It's my belief that the effects we call "shock" are in truth a combination of dramatic blood pressure loss through massive tissue damage and perhaps some trauma to the central nervous system.
A large, slow moving bullet will kill just as effectively, even if sometimes not as fast, because it destroys the lungs/heart/other organs and tissue just as well, though perhaps not as dramatically. The animal may (or may not) travel a bit farther, but it's just as dead.
The key point that I want to make is this:
No matter what bullet a person uses, it has to reach the vitals to be effective. I have personally seen some hollow point bullets splash (cause a surface wound without penetrating sufficiently), but this doesn't mean that ALL hollow point bullets will do this, or that ANY type of bullet will do it every time. I've also seen varmint type "ballistic tip" bullets do the same thing when pushed to high velocities.
Big bullet enthusiasts like those bullets because they penetrate reliably nearly every time.
Small diameter, fast moving bullet enthusiasts like those bullets because they tend to do massive damage as the bullet expands in tissue, along with the flatter trajectory of those bullets. The result is a quick kill. The problem with this is if someone uses a bullet INSUFFICIENTLY CONSTRUCTED TO PENETRATE RELIABLY. No matter what it's shape or nose construction, the bullet must penetrate well enough to reach the vitals.
If the bullet does that, then it's done it's job.
As a note:
Solid nose bullets might seem to be the key from what I've described above, but that's not necessarily the case. They may be needed on some game animals to shoot through heavy bone (in cases such as penetrating the skull on an elephant), but they tend to "pencil" through other organs. They'll kill those animals too, but oft-times cause insufficient damage in the tissue to cause a quick death. There's a balance point to be reached to achieve a quick, humane death of the game animal so that it can be recovered quickly.
A government that abrogates any of the Bill of Rights, with or without majoritarian approval, forever acts illegitimately, becomes tyrannical, and loses the moral right to govern-Jeffrey Snyder

RIP Linden33


Nothing "wrong" with balance AZ. However, after all your descriptions, you ultimately return to a fundamental conclusion that one bullet type is better "overall". In your case it's a bullet more substantial than an HP or "Ballistic Tip". This is precisely the source of all of the "mine is better" arguments, regardless of whether the "better" bullet is a light-for-caliber bullet, or a heavy-for-caliber one.
I would not argue with anyone regarding their personal observations. At the same time, I have been shooting very fast HP bullets for a long time. I suppose I have shot upwards of 50 head of big game with fast HPs. I have NEVER had a single one "fail". In fact, the single bullet that I would say actually "failed" would be a Remington CoreLokt. I have seen three of them shed their jackets, but I do not call that "failure" unless the animal wasn't recovered, or had to be chased a VERY long way over a long interval of time. I couldn't care less what the bullet looks like after it hits the animal if the animal is killed in a "reasonable" amount of time. The single CoreLokt that actually "failed" was one from a .270 that hit a black bear in the knee at approximately 150 yds. We found the jacket just under the skin of the knee, and the bone was absolutley without damage. The back of the jacket had opened like a can of beans, and apparently, the core had simply squirted right out. In my entire life, that is the single bullet I can ever recall actually "failing" to perform satisfactorily enough to take the animal.
As for HPs, I ONLY use HPs with very large meplats. At this time, Speer is the only manufacturer of such large-meplat HPs that I know - other than pistol bullets. The design of these large-meplat bullets essentially renders them a lead slug with a copper jacket that aids in increasing BC. After impact, they're basically just a lead cylinder.
Be nicer than necessary.


Oh, this ia a juicy one!

Ok, here goes....

I like a pointed soft point bullet for killing game. Deer, big game, hogs, you name it...

I like a fast caliber to deliver that bullet.
This is probably why I got "hooked" on the .223....After shooting very many, & I mean VERY many whitetails I have seen the results. If hit behind the shoulder with a fast moving, rapid expanding bullet, it seems I have had 95% of them drop without taking a step. As you get into the field dressing end of the job, you will see that the heart & lungs are just "Jello"...

To me this indicates that the energy was rapidly disbersed into the animal, causing the shock......THEN, the fragments sprayed the vital organs...totally devestating them.

You CAN go overboard on this, & I HAVE.........
I bought a Ruger No.1 in 25-06. I thought I would really shoot a screaching load with a hollowpoint bullet. A light hollowpoint bullet.........If I remember correctly, I was shooting an 87 gr.HP out of that 26" barrel at velocities nearing 4000fps. That's cookin' folks.

First, the bullet was very explosive.......I had it blow "chunks" out of a boars shoulder, & did the same thing to deer on a couple of occasions. The boar was just mad....not dead.
THUS......I agree with Az.....The bullet has to reach the vitals. No matter how much energy you put into the animal, if the vtals are left pretty much unscathed, then you have a problem.

I'm not sure I believe in "Premium" bullets all that much with one exception.....The ballistic tip & it's look alikes. I think that bullet DOES perform to it's reputation. The one variable I note to this, is velocity & caliber. I think it will perform differently out of a .223 at 3200fps than it will out of a .308 at 2900 fps.

I can see the .223 ballitic tip being a great performer on coyotes & the likes.....While I can see the .308 penetrating an elk shot behind the shoulder with enough force to anchor it. I attribute that to bullet weight in this instance. I think it would fragment & make "Jello" out of the vitals.

I know, I know.....You guys that think an elk can't be killed with anything but a Barnes X bullet, must think I'm nuts....go ahead & laugh.
In my humble opinion, I think the very deep penetrating, not much expanding, cost an arm & a leg bullets are frankly a fad. I don't think they have enough force when they hit an animal, nor do they leave a "devistation cavity" large enough for me as they "pencil" thier way through the animal. You'd better hit bone guys.....if you want that elk down right there....that way the bone fragments can do the job your expensive bullet is supposed to be  doing...

Gitano, the only "failure" I ever had with a bullet was corelockt 7mm mag. It was shooting a doe for meat at about 45 yards as she was grazing. Bang! right behind the shoulder....That doe was still standing there! I promptly put another round in her. She dropped like a rock!
Upon getting to her, she had 2 holes....about 3/4" apart, behind her shoulder. The first round had failed to expand at all. Simply punching right through her with NO energy released at all. What a great dhance for me to see the effects of a shot with one bullet doing it's job, & another failing miserably.

As far as hydro-static shock......Well, if you slow down those shows that show the animal being hit by a bullet, there is definately a wave that physically disrupts the tissue.....How much damage that does to the animal is anyones guess, but that boar with the chunk blown out his shoulder sure meant business after that shot...LOL.

Remind yourself often to SEE not just "look".

Daryl (deceased)

QuoteThe problem with this is if someone uses a bullet INSUFFICIENTLY CONSTRUCTED TO PENETRATE RELIABLY. No matter what it's shape or nose construction, the bullet must penetrate well enough to reach the vitals.
Actually Paul, I didn't mean to discount hollow point bullets.  My intentions were to point out that not all bullets of the same nose construction are built the same way.  Jacket thickness, as well as the lead to jacket bond also play a major affect on bullet performance.
I have personally seen hollow point bullets shot from a 22-250 that splashed.  Only a couple of times, but they did splash.  I've also seen it happen once with a Ballistic tipped bullet.  I've not shot many head of large game with these (my preference is for a well constructed soft point bullet), but rather several hundred coyotes.  In each case a second shot performed the way it should have.
I've also seen one jacket separation with a Sierra BTSP (not a hollow point) bullet on a coues deer.  The jacket was recovered from the hide of the off side hind quarter, and no bones were hit as it passed through the lungs.  For a bullet that should be able to take elk (175 gr from a 7mm mag), I was less than impressed.  If that round had been used on an elk hunt the following week rather than on that coues deer, I fear that the bullet would have failed to kill properly.  On that shot a shoulder blade was hit, and I often wonder if the bullet that came apart would have gone through.  I doubt it would have.
I'm not for any particular bullet type for all hunting applications; rather, I believe that a person should match the bullet to the game and then place that bullet correctly.  Like you, I also now shoot a .17 Remington with 25 grain hollow point bullets (Berger match) at about 4000 fps.  The bullets I use work well for what I use them for, but I would not use them for large game.  They will not exit a broadside coyote, and for that reason I question their ability to penetrate larger game.  At the same time, Hornady V-max (hollow point) bullets WILL exit a broadside coyote from the same rifle at the same velocity, and were I to have to use that rifle for deer or other such game the Hornady would likely be my choice.
Both are hollow points, yet each performs differently.  It comes down to bullet construction rather than just nose design.
Take care,
A government that abrogates any of the Bill of Rights, with or without majoritarian approval, forever acts illegitimately, becomes tyrannical, and loses the moral right to govern-Jeffrey Snyder

RIP Linden33


Actually, my intent with this post was NOT to initiate any particular discussion over the relative merits of a particularl bullet design, but rather to see what you folks think of the "work-power-pressure" analysis as a method to quantify terminal performance.
My daughter was waiting for the computer when I resonded to AZ, so my response may have appeared 1) a bit "terse" and 2) sounded like I was defending HPs. I didn't mean to be abrupt, and I certainly wasn't defending HPs. I gave that up a long time ago. I used 'em, never lost an animal and was pleased with their performance. Nowadays, I'm getting "into" fat, big around, soft lead bullets. In the end, my fundamental belief is that if you hit 'em "where it hurts" they're gonna die regardless of the bullet used.
Be nicer than necessary.


I know you were not trying for a bullet type debate here, Gitano.

And I agree with you. When you shoot an animal through the boiler room it will go down.

Bullet design plays a role in the comparison though. I use PSP bullets in my .223 & my .308 as well.

About the only way an accurate comparison can be done is to theorize using the same bullet design for each caliber....
For example.....a PSP bullet in .223, a PSP bullet in 30-06, and a PSP bullet in .458.

On top of confusing hunters & shoters with minute differences in say a 7mm Mauser & a 270 win., the gun writers are touting & selling the new "Gotta Have" bullets that fit them....

In my opinion a 30-30 winchester will put a bull elk down just as good as 300 Win Mag.....Just at a shorter effective range.

Remind yourself often to SEE not just "look".


Now you've started an interesting debate.
My opinion (purely subjective) is that the reason why HP bullets are effective when placed corectly was described by AK:
"To me this indicates that the energy was rapidly disbersed into the animal, causing the shock......THEN, the fragments sprayed the vital organs...totally devestating them"
The high velocity HP is more likely to loose partcles, each of which causes a secondary wound channel and therefore causing MORE DAMAGE than a bullet that retains its weight and punches a single hole.
If the bullet does not have to traverse a lot of non vital tissue to reach the vitals, these secondary wound channels will be in  the vitals and is what causes quicker "death". I would postulate that if you compare high velocity solid (small diameter) with a low velocity (larger diameter), the higher velocity would not be more effcetive in "killing" the animal!!
Now, there is one undisputed factor: it is true that high velocity bullets are more likely to "drop the animal in its tracks".  The most likely explanation I have heard is as follows:
There are several large "nerve nodes" in the flanks of an animal. The effect of the "bullet shock" on these could conceivably cause temporary paralysis of the animal.  If the bullet also causes enough damage to vital tissue, the animal will die before the paralysis wears off. The fragments from the high velocity HP causes sufficient damage to cause death before the animal recovers from the paralysis.
Slow bullets do not cause this "shock induced paralysis" and the animal will therefore run until the damage to the vitals causes death.
I do not subscribe to the opinion that the "energy transferred to the animal" contributes to damage.  The "shockwave" simply causes bruising which does not add to the fatal trauma. What is fatal at the end, is the actual size of the wound channel (or multiple channels if the bullet breaks off pieces).
There is one further exeption to this rule. A mushroomed bullet, has a slightly rounded frontal suraface. If you compare it to a flat point bullet, the tissue has to move a much higher velocity to the side to get "out of the way" of the moving flat surfaced bullet. Whereas the rounded bullet therefore causes a wound channel slightly smallar than its diameter (tissue is pushed to the side but it springs back after the bullet passes), the flat point bullet will cause a larger permanent wound channel (compared to its diameter), it crunches a hole, instead of slipping through the tissue.  This is why flat point handgun bulltes are more effective than round nose bullets.
I don't know if you have seen the hole punched by those bullets with the "shoulder". Whereas a "normal" bullet makes a hole in the skin that appears slightly smaller than the bullet, the hole made by these bullets look as of they have been "punched" with one of those punches to make holes in paper exactly the size of the bullet. Nice neat and round.
The failure of material to move to the side is clearly demonstrated if you look at the difference between holes punched in a paper target. A hole punched by (say) a 22 Hornet, will have a section around the edge showing paper "bent inwards".  The same hole punched by (say) a 220 swift, will have much "cleaner cut" edges. If I shoot at the same target with both my 22 Hornet and my 220 Swift, it is easy to tell the holes apart. The Swift bullet moves so fast, that the target material cannot accelerate to the side fast enough to get out of the way.
Similarly, I'm sure you've all seen the nice neat holes punched by wadcutter type bullets (even though they are slow bullets).
Ok guys, you can now climb in and shoot me down in flames.


Here is an example of a bullet with a "shoulder" that "cuts" a neat hole.



There are a couple of places I would disagree, but my arguments would be based solely on speculation, not any semblance of empirical data or analysis. As such, it is hardly more than 'hot air'. However, so that I do not appear coy, I'll state where we differ in opinion.
First, I don't think the "secondary channels" are significant with respect to the "immediacy" of death observed so often with HPs. Do they ultimately contribute to death - you betcha. Remember, we're talking specifically about the "exploding" particles of an HP or other frangible bullet here. Observation suggests that the "hammer effect" is "instantaneous". The effects of multiple secondary wound channels would not be "instantaneous" in my opinion.
Second, I also think that "bruising" is non-trivial. Of course how bad the bruising is would determine it's ultimate contribution to death. However, I believe that if when you open the chest cavity and you see a badly bruised heart, that single damage could very well have lead to the immediate "loss of feet" by the animal, and then the rest of the "DTD" would have time to lead to physiological death.
The "nerve nodes" is a new one for me. While I'll have to be shown those nodes, I would agree with your general premise with regard to "shock". Namely, that whatever "shock" occurs, it may very well "stun" the animal long enough so that DTD results in physiological death. This reminds me of an observation I have seen a few times.
I have shot a few animals, that at bullet impact, did not move AT ALL, or ONLY dropped their heads. Every time this has occured, I assumed I missed and fired again. In all cases except one, by the second shot, I realize that I haven't missed and quit shooting. When I take the animal apart, I always find that the first shot was definitely lethal. The conclusion I have drawn, is that the bullet hit the animal at just the "right" moment in its respiratory cycle, effectively "knocking the wind out of it". Those that have had the wind knocked out of them, will know exactly how "paralyzing" the event is.
The one time I didn't quit shooting after two shots was when I actually wasn't even the primary shooter. A good friend of mine was shooting a decent 45" bull moose standing picturesquely broadside at just about exactly 100 paces, using my handloded 150 grain bullets in his .30-06. At his first shot, I could clearly hear the "whack" of a solid hit. The moose had its head down when Jim shot, and it didn't move a muscle. Jim shot again. Again the BOOM-whack sequence. Again no response from the moose. Jim shot again. Again the same response. I asked Jim if he minded if I shot. He said "No", and I shot my 7x300 115 grain HP into the moose. BOOM-WHACK! No response. BOOM-WHACK. NO response. All of this took probalby the better part of 30 seconds. At that point, Jim and I simply stared in disbelief wondering if "Twilight Zone" music was going to start to play. A few seconds later, the bull's butt went down slowly, followed by his shoulders. When we got up to him, we found our five shots could be covered by the palm of one hand. By the way, all Jim's 150s went completely through, and the 115 grainers were found on the far side under the skin. :)
Killing critters is often a very strange "thing". I remain committed to the premise that you can use just about any bullet you want in just about any cartridge you want, and if you put it in the chest cavity, the critter's gonna die. If it's a Cape buffalo, or hippo, or brown bear, you better just hope it dies before it gets to ya.
Be nicer than necessary.


"I don't think the "secondary channels" are significant with respect to the "immediacy" of death observed so often with HPs."
Agreed.  The "shock" (or whatever it is) and the death caused by the secondary wound channels are separate events. The "shock" would occur even with a non frangible bullet. With a non-frangible bullet, the animal might not die (physiological death) before the shock wore off if the "single hole" did not cause sufficient damage to "bleed the animal to death" before it recovered.
Something else which has been widely observed, if the first shot is not a killer, animals often appear to have a resistance to follow-up shots killing them instantly. The phisiological explanation for this is the animal's "shock reaction", large amounts of adrenalin and the phisiological changes brought about by this (which among others causes blood reservoirs such as the spleen to "pump" blood into the circulation, increasing the amount of blood which have to be lost before blood pressure will drop and cause death).
The observation regarding the "nerve centres" in the flanks came from a pathologist, I don't have enough knowledge to argue the point but it seems the most plausible explanation compared to some of the other wild theories.
One of the most improbable theories I've heard is that the "shock" acts on the blood in the vessels like the hydraulics in a car's brake lines and the pressure so transmitted along the blood vessel causes vessels in the brain to burst resulting in death.


About the moose not going down...I read an account (with photo's) on the internet, written by an outfitter in Africa that had a client dhoot a cape buff. The guy used a .375 HH. The round was put through the boiler room....There was a cloud of dust raised by the impact of the bullet....Immediately the buff wheeled & ran into the brush.
Of course the outfitter & hunter had to follow.
I remember the outfitter was really hating his job by then....They flushed a couple of cows in the dense brush. After extensive trailing the buff was found dead in the tangle.
Upon field dressing the animal, it was discovered to have a heart completely hulled, through & through by the round. The photo I saw had the guide's finger poked through the hole. He estimated the buff was on it's feet for 3-4 minutes....

THAT was the interesting part to me.....What could a hacked off cape buffalo, or a big grizzly do to a guy in 3-4 minutes?

Indeed, hunting & the taking of animals is an odd occurance sometimes.

Remind yourself often to SEE not just "look".


I'm going to have to disagree with CAfrica that the shockwave does not contribute to the death. That shock is part of what disrupts the CNS. It also increases pressure within the body of the animal and breaks blood vessels. These blood vessels include things like the aorta, superior and inferior vena cava, and other various major blood pathways without which no animal can live.
 This is a very interesting discussion.
Ask not what your government can do for you. Ask how your government can go away and get out of your life.
The unarmed man is is not only defenseless, he is also contemptible.
Niccolo Machiavelli


This is a fascinating thread and were it not for a rehabing right shoulder, I would love to participate more extensively. However I do want to ask what may seem to be an odd question. If the shock related to the release of energy in a contained hydraulic area is not real then why is it possible to explode small amounts of explosives under water and kill fish. The fish will not show any type of penetration wound or other disfigurement. It has always been my assumption that they were killed by some sort of shock wave that was transmitted by hydraulic force. If this is in fact the effects of a shock wave experienced from the exterior, it would seems that a shock wave with point of origin on the interior of an animal would be even more devastating. If this is true, there must be some way to account for the realease of the energy that happens within a closed system such as an animal when energy is introduced. It doesn't just disappear unless the bullet goes completly through the animal. Even with total penetration there would be significant transmission of force even from the introduction of a projectile as small as 22 caliber. Just a thought based on watching the performance of a great number of different bullets impacting on thousands of praire dogs.