Why do manufacturers make underpenetrating loads for defense?

[Rampant_Colt]

I've noticed a lot of loads that are designed for personal defense, put out by a lot of companies, either fall short of or barely meet the 12" penetration requirement in ballistics gel. IIRC, the FBI recommends 12-18", and I'd personally prefer something on the later end. It seems form comments on the various ammo that a lot of people agree with me. Too often I see "it's a good idea, but the load is light and likely to underpenetrate" or "it only has 11 inches of penetration, I wouldn't use it."

Do these companies not test their products before-hand, or do they go by a different requirement?

For me, it's pretty much gotten to the point where I just carry the heaviest bulk hollowpoint I can find.

You'll find your answer HERE

 

[Skribs]

You may be in love with the idea of overpenetration and shooting a minimum of 12-16" through gelatin, and that's fine. But it's no more correct than someone that prefers less penetration.

If the bullet doesn't penetrate deep enough to reliably hit vitals (assuming it was aimed at the vitals), then it is much less likely to cause an involuntary stop. That isn't opinion.

Huntsman,
180 grain is already getting pretty heavy. I'm talking more about the .38 SPL rounds which use 90 grain bullets instead of 158 grain, or 9mm rounds that use 115 grain bullets instead of 147.

 

[writerinmo]

I have one firearm that I would seriously be concerned about overpenetration, but it's doubtful that I would grab my Mosin over the AK or any of my pistols.

 

[coloradokevin]

In other words, if a .223 stops in the body mere millimeters from the backside, you don't gain an "energy transfer" compared to the same bullet that goes all the way through (that myth has been stated repeatedly for years in some circles).

It isn't a myth, it is fundamental physics.

Let me edit my last statement to speak more precisely: In other words, if a .223 stops in the body mere millimeters from the backside, you don't gain any MEANINGFUL "energy transfer" compared to the same bullet that goes all the way through (that myth has been stated repeatedly for years in some circles).

The idea that a bullet stopping within the body will transfer a more meaningful amount of energy to the subject than a bullet that exits the body is not supported by any ballistic study I've ever seen. This conjecture has been tossed around for years, but the bullet doesn't kill because of energy transferred by failing to fully penetrate; the bullet's energy won't "knock down" the prey.

I'm not a physicist, and I can't give you a perfect scientific explanation of this fact. But, here it is in layman's terms in a video (as they state, per Newton's 3rd law, that energy is also transferred to the shooter in terms of recoil -- I'm sure in reality the weapon system absorbs some of that energy). Has recoil energy ever had a meaningful effect on your ability to stand?:

http://youtu.be/QCzD5uhSViY

There are tons of articles on this subject, if you look for them. Here's a quick find over on Chuckhawk's site:

http://www.chuckhawks.com/myth_muzzle_energy.htm


Put another way, by the bullet energy argument, a fast moving .223 round that exits the body and continues to move at a high velocity is a bullet that has failed to transfer much energy to its target. On the other hand, a 9mm bullet that stops within the adversary has managed to transfer all of its energy to the subject. But, the rifle bullet has clearly proven itself to be a more lethal round.

Nevertheless, for the purposes of this thread it seems more important to find a bullet that has adequate penetration capability, but not so much penetration that it causes unnecessary risk to parties who aren't involved in the gun fight. That can take us back to the good old 12-18" of penetration argument (if you support that FBI's study on this subject).

 

[Loosedhorse]

you don't gain any MEANINGFUL "energy transfer"...

The idea that a bullet stopping within the body will transfer a more meaningful amount of energy to the subject than a bullet that exits the body is not supported by any ballistic study I've ever seen.

"Meaningful" cannot be determined by ballistic studies. They have no way of determining if a .223 delivering all 1250 ft-lbs (typical) of its energy to its target is "more" or "equally meaningful" than if it delivers only 1100, or only 950 ft-lbs of its energy.

To determine that, we'd need a database of how attackers respond when being shot with the same caliber round but with bullets designed to either stay inside the body or to over-penetrate with given residual energies.

One often hears that bullet velocities "over 2000 fps" are needed to change the main wounding mechanism from direct bullet-crush injury to the more distant injury caused by cavitation and bullet fragmentation. Perhaps this is the source of the idea that any energy deposited in the body beyond whatever a .223 at 2000 fps would produce is "not meaningful."

But that doesn't make sense. If that were so, why would we standardly use a .223 round going 1200 fps faster? If tissue cavitation is the main mechainsm of injury, and is related to energy deposition, how can we--without experimental data on stopping attackers--determine how "meaningful" any given loss of energy transfer is?

(The question "how can we--without experimental data on stopping attackers--determine how 'meaningful' any given loss of penetration is?" also applies.)

BTW, I like the article you pointed to a Chuck Hawks. But the significance of muzzle energy vs. penetration is different when the animal hunted is a prairie dog or a Cape buffalo--and of course the human attacker is in the middle somewhere. And even with a Cape buffalo, my guess is that most hunters would prefer a high-energy-deposition round that penetrates well compared to a low-energy-deposition round that penetrates well.

 

[Skribs]

LH, on the .223 round, I know the Army uses it at that velocity because the specific bullet needs to be going 2700 FPS to reliably fragment, and 3200 FPS makes that a reliability at distances they will expect to be shooting.

Bullets do need to dump some energy in order to cause the cavitation. Some of those rounds that tumbled late on the AR-15 link at the top of page 2 didn't cause much of a wound tract until after several inches of penetration. However, they also caused less when they slowed down. A round that stops is a round that slowed down way back.

With a non-rifle round, you're not even worried about the cavitation effects, and the energy transfer idea is null. They deal their damage by poking holes. If the bullet stops, it poked less of a hole. If it stops short of vital organs, it just caused a flesh wound.

 

[Driftertank]

If a .223 bullet stops within millimeters of entering the body, it likely had much less energy going in than a round that went clear through. If they started out with the same energy, and bullet design is what caused the rapid stop, there WILL be some massive localized tissue damage from the propagation of the energy through the tissue...the energy has to go somewhere. But there is minimal risk of exsanguination, and unless it impacted close enough to a vital organ to damage it, you likely only caused some muscle to turn to goo. That's what hydraulic shock is all about.

Problem is that handgun rounds don't have enough energy to cause gooification. They basically only damage tissue they actually come in contact with. So the "ideal" handgun round would impact, expand as much possible, and travel clear through the body, expending all it's energy, dropping harmlessly to the ground on exit. Since that won't happen, i personally prefer a bullet that gets big and drives deep. Other opinions welcome.

 

[Shawn Dodson]

The 12" minimum is because law enforcement engagements oftentimes include shooting through barriers. Civilian SD encounters rarely do.

There are many everyday situations in which a private citizen may have to shoot through concealment to land a hit on an attacker, including circumstances identified in “A Word of Caution about Hornady’s Critical Defense Handgun Ammunition” at - http://www.firearmstactical.com/tacticalbriefs/2006/04/main.htm

There is no part of the human body that requires a bullet to travel 12" to reach vital organs, so I don't require my self defense rounds to pass that test.

A bullet can lose as much as 30% of its total penetration potential after it first perforates an arm. Thus a bullet that normally penetrates 10” may now only penetrate 7”. If the bullet penetrates 4" of arm then it may possess only 3" of remaining penetration potential to penetrate the body after it first passes through the arm. Depending on the attacker’s angle and body position this may not be enough penetration to reach and damage vitals.

Full penetration offers several major advantages. First of all, it creates two holes for blood to come out of. This doubles the flow of blood (at least) and thereby hastens shock.

The “two holes creating greater blood loss” theory is more myth than reality. Bleeding produced by a handgun bullet is mostly internal – blood leaks into the thoracic (chest) and abdominal cavities – there may be very little blood that actually leaks outside the torso.

If an FBI round over penetrates and injures someone, well, the injured now has to sue the federal government; even if there is a judgment, the agent who fired will not have to pay. However, if your bullet over penetrates and injures someone, there are fewer barriers to suing a private citizen, and you'll get the bill.

Many cases of “over-penetration” are the result of hits along the periphery of the torso, in which the penetration path through-and-through is less than the penetration path encountered during a solid center-mass hit.

Hence you can choose a bullet that penetrates 8” but if it hits along the periphery of the body it, too, may “over-penetrate”.

Anecdotal reports of “over-penetration” usually do not include a description of the bullet’s penetration path through the body.

 

[Skribs]

Many cases of “over-penetration” are the result of hits along the periphery of the torso, in which the penetration path through-and-through is less than the penetration path encountered during a solid center-mass hit.

Also if you miss, you "overpenetrate" by not hitting anything.

 

[Cosmoline]

Energy which does not damage tissue is not meaningful.

Bleeding produced by a handgun bullet is mostly internal

That depends on what you hit. But there's no question, medically, that a second hole for blood to exit from (preferably a larger one) accelerates blood loss and brings on shock faster. That's why first aid attempts to plug those holes. It's also a major reason for wanting two holes on game animals. Anyone who's seen the big gory exit hole with lots of blood oozing out of it can attest to that.

I have one firearm that I would seriously be concerned about overpenetration, but it's doubtful that I would grab my Mosin over the AK or any of my pistols.

Actually the Mosin provides more than enough power to do pretty much anything you want. If you want a 3,200 fps exploding SP, you can easily rig one. Whereas, for example, a low velocity heavy round from a handgun will keep on trucking much further through barriers.

 

[Certaindeaf]

Back in the olden days, manufacturers went light and fast (super-vel etc) because handgun bullet design was in its infancy. Of course, the various 240gr .44 mag HP's going at 12bajillionfps wouldn't open up on game on a bet though.

 

[Shawn Dodson]

But there's no question, medically, that a second hole for blood to exit from (preferably a larger one) accelerates blood loss and brings on shock faster. That's why first aid attempts to plug those holes.

Medically, a chest tube is inserted to drain blood to keep internal bleeding from collapsing the lungs. If blood flowed are readily out the external bullet hole as you suggest the chest tube wouldn't be necessary.

First aid to the to the bullet holes on the outside of the torso doesn't stop internal bleeding.

 

[Cosmoline]

There often isn't an exit wound, precisely because so many handgun bullets stop short. And while internal bleeding is a potential threat, you're talking about someone who's already survived long enough to get a chest tube. That's not a bullet that worked well enough. If the blood drains out faster, then the circulatory system depressurizes faster and shock sets in. You don't have to deal with a lung collapse from internal bleeding because you're dead. And conversely a bad guy who's suffering from slowly accumulating blood in the cavity is still going to be able to shoot back. You want to drain his blood as fast as possible or get a CNS hit because those are the only reliable ways to stop him.

It's why hitting the heart or a major artery is so often fatal, because so much blood is lost so quickly.

But you're absolutely correct that single-hole small caliber handguns don't tend to produce a lot of blood. That's one reason they don't work too well. I remember going right past a dude that had just been shot a minute earlier in a drive-by with a small caliber handgun. He was just sitting there holding his gut. I thought he was intoxicated and went on. There was no blood, no nothing. And he survived after a trip to the hospital. Never would give a statement to the cops.

What you want, in a self defense scenario, is something that does more than just give a man a belly ache and a surgery bill. Otherwise the threat is not neutralized and can continue to shoot at you.

 

[Skribs]

This is all interesting, but I think some of you are missing the point - if the bullet didn't penetrate deep enough to cause significant damage to the vitals, it doesn't matter if the bleeding is internal or external. The 12-18" penetration recommendation isn't to provide a through-and-through, it is to allow the bullets to sufficiently damage vital organs.

I was mostly referring to pistol rounds when I made the OP, although rifle rounds kinda got tagged with it (and I was thinking about the duplex load of #2 and #4 birdgshot). With a pistol round, even if most of the bleeding is internal, a deeper hole or a through-and-through will increase blood loss. It might not double it, but it will increase it.

As to rifles...if they dump their energy before reaching vitals and slow down to a velocity that will not result in a vast cavity, then the actual damage to the vitals is going to be very small. The large amount of damage done will be before it reaches the vitals. I'd rather have something that causes a medium-sized cavity and continues through than something that causes a large cavity but chokes too soon.

Remember, we're not just talking about how much energy is expended, but how it is expended and what it is doing with the energy after it is spent. It's not just how big of a hole, but where that hole is - both in shot placement and in the depth you penetrate to.

 

[FIVETWOSEVEN]

I thought that the requirement comes out of the possibility of shooting through an arm which takes a lot of the force out of the bullet impact when it reaches the vitals. Whenever I see a test to see if it penetrates 12"s, I rarely see a barrier but just the Gel itself.

Civilians are just as likely to have to penetrate barriers as LE in a shooting. A bullet may, or may not need to penetrate 12" to reach vital organs. It depends on the angle of the shot. Even then it has to completely penetrate vital organs, not just reach them.

No we aren't, we won't have to be shooting through car windshields or doors near the same as LE. Sure it could happen since I hear about people pointing their gun to a potential threat through the car door but when has that ever happened? Only case I remember reading was when a guy put a slug in his shotgun and shot a home invader that took cover behind his fridge or the many cases of people shooting through their bedroom door but that's it.

 

[Remllez]

I was always under the impression that hollow point ammunition was designed to cause more instant shock to the body using less shots thereby ending hostilities quicker without necessarily causing death, the theory being less individual wounds less chance of death.

Full metal jacket which relies more on blood loss rather than energy dump usually requires more shots to stop hostilities thereby increasing the likelihood of more internal damage and blood loss which in turn leads to more deaths.

The theory behind JHP was to incapacitate/injure rather than kill.
I may be wrong and please don't flame me too badly, but for some reason this theory seems to make sense to me. YMMV

 

[allaroundhunter]

I was always under the impression that hollow point ammunition was designed to cause more instant shock to the body using less shots thereby ending hostilities quicker without necessarily causing death, the theory being less individual wounds less chance of death.

Full metal jacket which relies more on blood loss rather than energy dump usually requires more shots to stop hostilities thereby increasing the likelihood of more internal damage and blood loss which in turn leads to more deaths.

The theory behind JHP was to incapacitate/injure rather than kill.
I may be wrong and please don't flame me too badly, but for some reason this theory seems to make sense to me

Let me try to correct some of this.

Hollow point ammunition was not designed to cause more instant shock. Handgun rounds are not traveling fast enough to deliver that kind of energy. They are designed to expand and cause a larger, (hopefully) more incapacitating wound than an FMJ round that is zipping through a body.

A JHP round is more lethal than an FMJ round, so the "less individual wounds less chance of death" is most certainly not true.

The theory behind JHP was to incapacitate/injure rather than kill

The theory behind the JHP is to expand to cause a larger wound tract and a larger loss of blood, not to attempt to save the life of its target. It is up to the shooter as to whether the shot will be incapacitating or not, and the shots that will incapacitate an attacker the fastest, also have a tendency to be the most lethal.

 

[Sam1911]

I was always under the impression

Not really. The lines between theory and practice get pretty blurry.

The primary factors are that hollow points are just another version of expanding/deforming bullet. When they strike something soft-ish they change from pointy needles to a big bull-dozer blade tearing through the tissue.

Instead of poking a little hole in something, they make a bigger, nastier hole in the target, grabbing tissue and tear it apart. There is no way that one can support an argument that a hollow-point is reasonably/realistically less likely to cause death than an FMJ.

The energy dump idea is probably highly over-rated, but what isn't over-rated is that the bullet's enegry is being used to a)deform the bullet itself, and b) act on more tissue because that bullet is getting bigger.

Like opening a drag chute or a sea-drogue, that very aerodynamically inefficient shape being forced through the medium does slow the projectile down quite a bit because that energy is being diverted into those other tasks.

One of the benefits, or simply "trade-offs" rather, is indeed lessened penetration, vs. FMJs.

FMJs can wound through a couple of means, like yaw and fragmentation if conditions are right. There isn't though a driving philosophical reason behind using them that says they're more likely to cause death. The only reason they are used -- at all -- is a historic (and flawed) belief in a kind of battlefield ethics that said that "civilized" (white) people shouldn't shoot each other with "inhumane" bullets designed to cause extra damage. The idea is, of course, absurd, but there's more than a century of social momentum behind not arming our soldiers with the most lethal ammo they could have...so we don't.

 

[Skribs]

That sounds like political BS to me, Remllez. The goal of a hollowpoint is to cause more damage within the wound tract.

With a pistol, if you penetrate through-and-through, adding more power doesn't do anything. Making the bullet wider does. Compare the recoil and expanded size of a 9mm JHP with a .45 ACP and the 9mm wins on both counts. You're still counting on blood loss.

With rifles, the hollowpoint or yawing/fragmenting rounds dump energy better, creating a larger wound tract. Larger wound tract = more blood loss.

Anything saying hollowpoints are less lethal is just politics or marketing. Excepting underpenetrating loads, they are more lethal. Their purpose is to end the threat faster.

 

[Loosedhorse]

Energy which does not damage tissue is not meaningful.

Well, that is a reasonable assumption. But it may not be true.

Just as many have taken to the assumption that 12 inches is the right "minimum" penetration, they have taken to the assumption that a handgun round with a large "energy dump" will not stop an attacker any better than a round penetrating the same amount with a small energy dump. But we don't know that.

Recall that the majority of assailants stopped by hangun fire don't die, and so were stopped by something other than a fatal wound. So, while we know that penetration of vital organs is needed for fatal stops, we do not know all the factors that influence the non-fatal stops (sometimes called "psychological stops") that apparently accout for most stops.

Hence you can choose a bullet that penetrates 8” but if it hits along the periphery of the body it, too, may “over-penetrate”.

That doesn't change the fact that a bullet that penetrates 18 inches in gel can be expected to overpenetrate more frequently (and with greater residual velocity) than a round that penetrates 11 or 12 inches.

Again, these days it's a bit of an anachronism, supposing we must choose between a low-energy dump round that penetrates 18 inches or more, and a high-energy dump round that penetrates only 8 inches. We can have both energy dump and penetration.

For example, there's the .40 S&W 125gr Barnes Tac-XP, which can apparently be pushed to over 1400 fps and yet seems to still penetrate just shy of 18 inches in gel. And typical "bad ammunition" (like the infamous Hornady Critical Defense 9mm) actually penetrates 11 inches, just shy of "acceptable."

It's perhaps worth remembering, too, that the most common "bullet failure" in ammo tests is an HP that clogs with barrier material (like denim or gypsum), fails to expand, and then acts more like FMJ than an HP. So in use, the penetration of anything except the "latest and greatest" HPs may actually be greater than advertised (if clothing or other barrier is encountered).

 

[TT]

Brickeyee: It is called a free market.

Yup. Not everyone subscribes to the 12” minimum theory. And there are plenty of 12+” loads on the market for people who do, so what is the problem?

 

[Skribs]

The problem is twofold:

1) Most places nearby sell the fast, light, underpenetrating loads.
2) A lot of the newer bullet technology (such as attempts at making more reliable expanding bullets) are something I would purchase if they made a higher penetrating (15-18") load.

 

[Remllez]

I was merely offering an opposing viewpoint....I never said it was written in stone and it may be political BS. But I'm still not convinced it's totally false. Let's call it food for thought.....

 

[Cosmoline]

The 12-18" penetration recommendation isn't to provide a through-and-through, it is to allow the bullets to sufficiently damage vital organs.

I suspect the recommendation is sales spin, trying to turn a shortcoming into some asset. More is better when it comes to penetration.

Well, that is a reasonable assumption. But it may not be true.

How can energy which does not damage tissue have an effect? Are you suggesting that there's a psychological distinction between a round that stops mid-torso and one that exits? Or that the person shot can even tell?

Full metal jacket which relies more on blood loss rather than energy dump usually requires more shots to stop hostilities thereby increasing the likelihood of more internal damage and blood loss which in turn leads to more deaths.

They all rely on tissue damage. A round that doesn't damage tissue is a round that bounces off. And while that may sting a bit, it's not really going to stop someone at handgun energy levels. Even in the case of kevlar jackets, the round is still doing tissue damage by pressing into the tissue causing bruises or broken bones.

The energy itself isn't doing anything unless it damages tissue.

Of course there is a valid efficiency argument as well. If the handgun slug has 300 ft. lbs on impact, you want to use as much of that energy as possible damaging tissue. So it's true that the non-deforming fmj or hardcast that still has 100 ft lbs on the flip side hasn't used its power to maximum effect. The problem is there's so little energy to play around with when it comes to handgun bullets, as soon as you start making expanding tips there are risks the round will fail to do much of anything.

And I'd argue that giving you an exit hole is a nice bonus, so that's not really "wasted" energy.

 

[Skribs]

Cosmoline, the 12-18" isn't a sales pitch, it is what someone at the FBI concluded is needed for them to use as a standard when they select ammo.

How can energy which does not damage tissue have an effect? Are you suggesting that there's a psychological distinction between a round that stops mid-torso and one that exits? Or that the person shot can even tell?

It depends on how that energy is spent. In a pistol round, as has been said, amount of energy is one of those things you put into the story problem that doesn't get calculated into the equation. For a pistol, it is penetration depth and bullet diameter. If you "expend 100% energy", it means the bullet penetrated less. Any extra past the perp doesn't help, but any less before an exit wound does nothing. So, you're right, the extra energy does nothing once you overpenetrate. But that just means you erred on the side of more penetration, as opposed to having a bullet that did less damage.

On the other hand, with a rifle, a rifle does its damage through the energy dump. However, the bullet continues onwards after the energy dump and the large balloon-like cavity with minimal velocity and damages things behind it. If you go here and scroll up for the chart, you'll notice that most of the rifle hits are leaf-shaped. They have the big cavity up to about 20 or 30 cm, and then they have a shallow cavity for another 10.

What this means is that the round is causing damage with the energy dump up until 20-30 cm, and after that functions like a pistol round. The energy stops being a factor once the bullet slows down - after that it functions like a pistol bullet. In order to get the energy to matter all the way through the target, instead of having something that stops in the target, you would need something that maintains 2000 FPS through the exit wound.