Energy Dump (rant)

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IMHO, the "energy" of a round that does not cause hydrostatic shock (i.e. handgun cartridges) only facilitates the damage of tissues by the crushing and cutting action of the bullet as it travels through those tissues. Expanding bullets are good because they open up to a larger size, and thus cut, crush, and injure more tissues as they move through the body.

Really, it doesn't matter if a bullet exits the body or not. It matters whether it has injured enough tissues to cause the person (or animal) to either stop their attack or drop (in the case of hunting). Shot placement is the most important thing, as this determines whether the tissues the bullet is injuring are vital and will cause immediate cessation of activity, or not.

Hydrostatic shock in humans and animals only comes into play with bullets going very fast, and it only causes damage when the temporary stretch cavity caused by the hydrostatic shock exceeds the stretch capacity of the organs affected, causing injury through tearing. This is why prairie blow up when hit by a high-velocity round within a certain range, the temporary stretch cavity caused by the hydrostatic shock is larger than the stretch capacity of the prairie dog's body. Thus, it blows up.
 
I agree with those who've pointed out that in a self-defence situation, over-penetration is undesirable due to the risk to innocent bystanders, whereas in hunting, an exit wound takes on new advantages. However, I think that the vital point has not yet been made.

Energy is defined as "the capacity to do work". This is why it's defined in foot-pounds: a foot-pound of energy is that amount of energy sufficient to move one pound of weight a distance of one foot (ignoring the effects of gravity, friction, etc.). So, in theory, more energy = greater work capacity, right? Well, it doesn't work out that way with bullets...

Peter Capstick gives a good example of this with his description of a buffalo hunt in Africa. This particular buffalo was socked with a .460 Weatherby Magnum - TEN TIMES! He continued running along until the last couple of shots, when he finally expired. All of the shots were well aimed, and all performed as expected (when examined, the buffalo's chest cavity - heart, lungs, etc - was shredded into ribbons). It took a total of over 60,000 foot-pounds of energy to put that buffalo down! Was this a failure? No - just that the buffalo hadn't read the ballistics charts, and didn't want to give up! I've also seen buffalo shot once with a .375 H&H, and go down almost immediately (I've done this myself three times). Does this make the .375 H&H a "more powerful" or "more effective" or "superior" cartridge to the .460 Weatherby Magnum? Not in the least!

The energy of a particular round is a nice ballistics figure, and has its place: but energy is only the capacity to do work. The target, on the other hand, has the capacity (to a greater or lesser extent) to resist the effects of that work. If you shoot a buffalo (or deer, or bear, or ...) that doesn't know you're there, and is not charged up with an adrenalin dump, the bullet is much more likely to take effect quickly. On the other hand, if that animal is alert, and scared, and running, the adrenaline dump is having its full effect, and doing the same amount of work to the animal will take much longer to have an effect.

The same applies to self-defence situations. We've all read the horror stories about criminals who were hopped-up on a cocktail of narcotics, alcohol and adrenaline, and who absorb an uncanny amount of damage before going down. There's the Chicago druggie who was shot 18 times with handgun rounds, and still kept shooting - it took two shotgun slugs (one to the head) to end his criminal career. There's the New York case of the hopped-up restaurant robber who was shot 18 times with .38 Special +P 125gr. JHP, and just stood there throughout the shooting (including two reloads), not moving, not falling down... at the autopsy, they reckoned his blood was orange and fizzing! The energy these guys absorbed was more than enough (in theory) to kill them (and in fact did kill them, after a time): but it was not sufficient to stop them. Was this an "energy failure"? No, not at all... just that they could absorb that energy better than the average target. (Makes one more aware of the value of a good central-nervous-system shot, too!)
 
Energy does work...but does it work to deform tissue and bone or just to deform the bullet itself? Is KE wasted mostly on deforming the projectile?
 
Another reason for wanting a bullet to go all the way through instead of lodging inside the bad guy... bad guys don't like the good guys to be digging out the bullet with their Leatherman tool without anesthesia. :D

In all seriousness, the amount of energy in normal pistol or rifle calibers do not do the damage to tissue. Its the use of that energy to crush tissue, bone and organs that does the damage. So, ideally, you want the bullet to just poke out of the other side of the skin, this way, all of the energy was used to crush tissue, instead of going outside. to crush the drywall and the pet cat.

Since you can't predetermine the bulletpath, you are stuck with 'guessing' as to how much energy to give the slug in order to go through as much bad guy tissue/bone as possible, without giving the good guy more recoil than is required. This is how they got to the 12-14 inches of tissue simulant penetration.

As said earlier, energy is used to crush tissue/bone, but the other part of crushing tissue/bone is the slug itself. If you don't have enough energy to drive the slug into bad guy body parts, you dont' have enough tissue damage.
 
Oleg,

I don't think that KE is wasted on deforming the bullet, if the bullet deforms in a way that makes it crush and deform tissue and bone more effectively. In other words, the energy necessary to make a good HP bullet open up isn't wasted if thereby more tissues are disrupted by the increased diameter of the expanded bullet.
 
It can't be all about penetration. Otherwise the difference between 45 caliber bullets and, say, 38 Spec. would not be significant. You'd either strike something vital or you wouldn't.

Some people have said that a spinal hit (CNS) often causes instant stops. Maybe a fragmenting or deforming bullet stands a greater chance of damaging something vital than a straight throuth-and-through. I liked the analogy to varmint rifle rounds. I think people are closer to varmints than they are to elephants and bears. We don't have that much armor.

I was just reading Speer's reloading manual and they noted that Gold Dot bullets were designed to expand but also survive some penetration (cover) also. Those needs do sound like competing qualities.

Above some velocity there is a temporary cavity formed that sounds like serious shock damage to me. How about a round that can cause a huge temp. cavity but not endanger when it overpenetrates (as a shotgun slug would). Anyone for really high velocity shotshell ammo?
 
Temporary cavities are irrelevant. Unless its permanent, you can't count on its wounding effects.

Permanent cavities are what is important, and it encompasses the permanent effects of the projectile, including any tearing/damage the shock impulse would do against the relatively elastic tissues.

What makes temporary cavities permanent is if the animal is smaller in size than the size of the temporary cavity. Thats why the hot 220Swift has 'explosive' effects against squirrels and ground hogs, while it makes for nasty shallow wounds on larger animals.

I wonder what the size temporary cavity is made by those depleted uranium fin-stabilized 120mm rounds. If its larger than a man, then you can say 'pink mist'. :uhoh:
 
I generally stay out of these discussions because I don't like to get flamed, but I am a strong advocate of kinetic energy and moderate penetration vs. momentum and deep penetration/overpenetration. You guys that like momentum/deep penetration, more power to you, and certainly choose what you are confident with. But please remember that rational people CAN disagree with you (and with Fackler et al.), and those of us who do favor light/fast/early fragmentation, or who believe that temporary cavity isn't necessarilly irrelevant, aren't necessarily idiots or ignoramuses. This is a complex subject, and there are good arguments on both sides.
I take a steel spinning target and shoot it with a 230-grain hollow point traveling at an average of 920 fps. Now the target weighs about 4 pounds and the bullet is producing about 430 foot pounds of kinetic energy. And you know what it spins the target a couple of times but nowhere near what it does if I hit with a 32-ounce hammer.
Click to expand...
What spins the plate is the momentum of the bullet, not the energy. Shoot the plate with a 40-gr JHP out of a .223 and the plate probably won't spin any harder than if it were hit with a .45, but you will get a crater in the steel. Momentum moves the target, while energy deforms the target.
 
I agree with Redneck and Preacherman

Redneck said it best:

if the bullet starts off with X ft-lbs of kinetic energy, and ends up with zero ft-lbs of energy, then X ft-lbs of energy was expended doing something. In this case, squashing stuff.
You do as much internal damage as possible, without the added risk of the bullet retaining enough energy to hurt somebody after blowing clear through the intended target.
The energy dump isn't intended to "knock them over" its to do as much internal damage as possible without sending the bullet to places unknown. Internal bleeding isn't any better for ya than external bleeding.

Me: An exit wound is not at all necessary for massive bleeding to occur, especially if the aorta or other large vessel is even nicked.

I add this: A bullet traveling through a body in a straight line will do less damage than one that corkscrews or arcs through, or creates multiple wound channels.

I also state: Waiting for a broadside shot through both lungs is an easier proposition when you're hunting than when you're defending against an aggressor that bleeds orange fizzy stuff.
 
If a big fat bullet stopping in a target was preferable to a thin, long bullet piercing through, why don't we see low-SD bullets being used against big game? Granted a bullet may still kill an animal even if it doesn't create a large exit wound, but I've never heard anyone argue that the bullet is doing MORE damage by stopping in the target and somehow "dumping" its energy.

It's not a question of favoring "momentum" over "energy." It's much more basic than that. Bullets typically kill by tearing big holes that cause a dramatic drop in blood pressure. Either that or you get lucky and hit the central nervous system. Those are the ways to kill quickly. Other ways will kill more slowly, but obviously those should not be the first choice in a time of need.

What I propose is bringing the hard-earned lessons of hunting into the field of self defense. If nothing else, it might cut down on the bravo sierra that seems to overflow from the handgun magazine gurus.

I don't think there's much disagreement when you boil it down. It may be a matter of what terms are being used.
 
If a big fat bullet stopping in a target was preferable to a thin, long bullet piercing through, why don't we see low-SD bullets being used against big game?
Click to expand...

Some are, but generally, they are used by handgun hunters because you are not going to get a lot of retained velocity at long distances.

Best bullet for tissue damage is a bullet with sharp edges, which means a cylinder (wadcutter). In all types of actions, its easier to chamber a round when its rounded a little bit. More if the cartridge case is too (bottleneck).

For a semi-auto pistol for self defense, you'd have to settle for a bullet that reliably chambers and ejects. I've seen some 1911s/Glocks that are do not chamber with semi-wadcutters, or fails to eject properly when the next round is a semi-wadcutter.

For a revolver, it would be difficult to speedload wadcutter rounds, as now, you have 5/6 rounds to properly align.

Cast Performance's LBT product line is pretty aggressive as far as wide meplats (flat part of the tip of the bullet). Here is what Garrett Cartridges have to say about wide meplats.


About temporary cavities and energy, I'm just reading through Duncan MacPherson's book 'Bullet Penetration', and he makes a valid point that unless the temporary cavity made exceeds the elastic limit of the tissue, you are just moving the tissue aside, and its going to go back where it was afterwards. If the temporary cavity exceeds the tissue limit, then it just became the permanent cavity. If the temporary cavity is bigger than the tissue itself, this is just another variant of the temporary cavity exceeding the tissue limit.
 
Can't always pick your shot on big game. All the accounts of african hunts for stuff like buffalo I've read, involved using an expanding bullet for the first shot, and solids to follow. First shot, you go for the vitals, and do as much damage as possible. Follow ups are usually whatever is presented, if thats the south end of a north bound buffalo you need quite a bit of penetration to put the bullet through the vitals, which goes back to shot placement. The bullet has to get there before you worry about expanding, non expanding, exit wound or no etc.
 
I think the reason that expanding SD ammo isn't used much on game is that it doesn't penetrate enough to disrupt the vital tissues in many game animals. Remember, humans are fairly thin skinned, and our sectional density isn't as great as many others in the animal kingdom. Thus, what may be adequate penetration to disrupt our vital structures may not be on game animals.

This is also why I'm not in favor of very light, fast handgun projectiles that break up upon impact. The wounds that they do are very wide (large) but very shallow, and don't usually penetrate enough to disrupt vital structures in the human body. Unless you hit someone just right, then that large wound isn't going to cause enough shock to incapacitate them, especially if they are wearing heavy clothing and/or they put something in the way of your shot, like an arm. I prefer to use a round that expands to at least .60 caliber and penetrates 14-16 inches in ballistic gelatin. Those seem to be the "magic numbers" that ensure a fairly reliable stop when fired into the center of mass. Ultrafast, ultralight projectiles such as the new zinc and aluminum bullets that are coming out now many times don't even penetrate 6 inches in ballistic gelatin, that's less than half my criteria for penetration. But, hey, everyone is free to make their own choices, I've done my research and chosen what I prefer to carry, and everyone else is free to do the same.
 
If the energy "Dump" was really the lethal element than Soft Armor wouldn't be of any use.

All of the energy is dumped when a vest is struck.

A bullet is not a bludgeoning weapon.
 
Oh THAT kind of energy dump! I thought this thread was about what happens when I eat too much bran and power bars :)
 
If the energy "Dump" was really the lethal element than Soft Armor wouldn't be of any use.
All of the energy is dumped when a vest is struck.
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The energy is absorbed by THE FIBERS OF THE VEST AS THEY BREAK, not the body of the wearer. It takes a LOT of energy to stretch and break a fiber of Kevlar or Spectra, and each of the hundreds or thousands of fibers that break upon impact absorbs that much energy from the bullet.

The wearer of the vest gets the momentum, but almost NONE of the energy (just enough to leave a big bruise).

In the case of hard armor (i.e., level IV external armor), the energy is dumped into the ceramic plate, progressively fracturing it and grinding the fragments into powder, while also grinding away the nose of the bullet.
 
Flesh/tissue is mostly water. You need 4186 Joules of energy to raise 2.2lbs of water by 1degree celsius in temperature.

A 230gr bullet going at 880FPS has 536 joules of energy (396ftlbs)!

Assuming that you have an infinitesmally small bullet, say the size of an atom with the same energy as a 230gr bullet going at 880fps, aside from poking a small hole, and heating up some tissues, and maybe causing some individual cells DNA damage, the person is still going to be alive after being hit. Heck, hit them with a gazillion of these and maybe their hair will fall out after a week.
 
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