Why do manufacturers make underpenetrating loads for defense?

The problem is the possibility that the bullet will require an unusually large penetration to reach vital structures well inside the body. This can occur when the bullet must traverse non-critical tissue; e.g., the extended arm of an assailant aiming his handgun, and/or an unusual bullet path angle in the torso, and/or an unusually fat or beefy individual. The probability of needing this extra penetration is a judgment call, but most people believe it is a significant factor and much more important than the relatively modest increase in expanded diameter achieved by reducing penetration depth (e.g., approximately 30% increase in expanded bullet diameter is achieved by designing to an 8 inch penetration depth rather than 12 inches).

Click to expand...

Any plans to redo these studies but factor in now that people are bigger? (That’s the finding of the latest Gallup-Healthways Well-Being Index, which shows that 63.1% of adults in the U.S. were either overweight or obese in 2009)

I'm thinking 12" won't cut it maybe 20" will, how about shooting those fancy SDHP into something the consistency of 8" of fat?

bottom line hit the vitals forget about what the bullet may do after that.

bottom line hit the vitals forget about what the bullet may do after that.

Click to expand...

Good advice, but...

Which brand of ammo always hits the vitals, again? I'll make sure to buy that one!

Even if we don't want to, we may in a gunfight find out that outcome hangs on what the bullet does to the attacker when it doesn't manage to hit the vitals. Which is why I am puzzled that there seems to be so little interest in looking at that.

a miss of the vitals is still a miss eventhough it is a GSW is an expanding bullet enough to compensate for a miss? or false hope that might bite you in the butt?

false hope that might bite you in the butt?

Click to expand...

The idea that any shot you fire--or any shot that hits--will actually end the fight might also be a false hope.

It's interesting: it seems to me that in order to criticize me for considering anything but penetration, you have to say that I'm depending on it.

a miss of the vitals is still a miss

Click to expand...

Hmm. Somebody better tell IPSC and IDPA that. For some reason, both organizations give you some credit for hitting anywhere on the target--they don't give you a zero if you "miss the vitals"--you get at least some points for every bullet that hits.

Real gunfights seem like that, too. Sometimes you don't hit anything vital, but the attack stops immediately; sometimes you hit something vital, but the attack goes on for long enough to kill you.

A hit centered on the vitals...

Click to expand...

The importance of penetration ASSUMES this, doesn't it--that you actually scored a hit "centered" on a vital organ. If you didn't, all the penetration in the world, according to the only-penetration-matters theory, won't help--you'll get no effect.

If bullets actually do at times---and we know it's most times--stop fights without hitting anything vital, that might be important, since precise aiming in the fading or absent light and the moving-target-moving-shooter reality of a typical gunfight will be dicey. That will make your needed A-Zone hit a hard thing to depend on--and you must depend on it, if the penetration-only theory is right.

Voluntary is largely irrespective of the bullet used (and often whether you even hit)

Click to expand...

Sounds like you're making another assumption. I've said many times that we don't know whether energy dump--which is influenced by the type and weight of bullet used--changes the probablity of a "voluntary stop"; but you seem to claim you know it does not.

Getting back to your question. We've said already that the main reason that manufacturers produce the loads they do is that people buy them. My guess is that one reason that people buy them is that, despite the dire warnings of the FBI, our graveyards are not lined with markers carrying the epitaph, "He shoulda used a load that penetrated closer to 18 inches in gel."



As I said before, without data, there is no scientific way to choose among competing theories. There's just opinion and choice. And so, the market lets us choose.

Changing the subject just a tad, when and if you get involved in a shooting, you best tell the court that you simply shot to stop the aggressor, not kill him if that's what happened. Not why you chose such a bullet based on what you read or assumed was factual.

A hit centered on the vitals that doesn't penetrate deep enough will not hit the vitals.

Click to expand...

Yep penetration should be #1 so why risk it with a bullet that could clog up or worse yet fragment, shot placement while not a given can at least be worked on with training but bullet failure won't be evident until it's too late.

I bet it'll really suck to hit COM but only to have a HP stopped by Carhartt and a Hoodie and 6" of fat

Not why you chose such a bullet based on what you read or assumed was factual.

Click to expand...

A bit off subject, as you say. But I plan to be able to explain all my choices: the gun I chose, the ammo I chose, why I was carrying at that time and in that place, and why I had no choice but to shoot to stop (as you reminded us).

Stopping Power basics

Mass x Velocity = Energy

Energy expended in the target results in damage

Energy that continues outside the target is useless

Wound Cavitation is the damage done to tissue surrounding the wound channel from the release of energy from the bullet

Tissue damage (wound cavitation) is what stops a threat, particularly if it is nervous tissue

An ideal SD round will expend all of it's energy within the target. This means that if a bullet passes through the target there is wasted energy. You will rarely be shooting through barriers for personal defense and you will also need to worry about an over-penetrating bullet passing through walls etc. in populated areas.

This is why fast light bullets that have high energy values due to velocity often do not do near the real world damage as slow and heavy bullets. Think .45 ACP vs. 9mm

Mass x Velocity = Energy

Click to expand...

Simply wrong.

Mass x velocity = momentum

Energy is mass times velocity squared divided by 2.

Energy = (mv^2)/2

And do not forget that grains are NOT mass, they are weight.

You have to divide by g (acceleration of gravity, 32 ft/s^2) to get mass.

I think a lot of folks would find this video interesting. (Warning: graphic medical images)

http://www.youtube.com/watch?v=tku8YI68-JA&list=FLdHkVjhMVf7HXRa-jRmDGaA&index=4&feature=plpp_video

What I take from this is:

1) Penetration on vital organs is key.

2) Most handgun rounds do not penetrate well.

3) Size of holes left behind is more important than energy transfer in handguns. (The bigger the hole, the more effective the round is, but it's up you to decide if you want fewer bigger holes or more smaller ones, I.E. 9mm vs .45)

4) Energy transfer in a handgun round is a joke. (9mm = 10 lb weight dropped from .75")

5) Even a .223 or .30 cal rifle round will only make a hole that size unless it tumbles. (It has to encounter a lot of tissue to start tumbling.)

6) 12" of penetration on ballistics gel does not = 12" on a human body.

etc.

I will echo that I do think the 12" recommendation is a bit arbitrary, for LEO, and I don't worry if my pocket pistol ammo stops at 11" in the gelatin tests. It doesn't under-penetrate, it just penetrates less than my 9mm or .45, but it is a balance of pocketability and power. Of course whenever possible I carry more firepower, but don't feel undergunned with my .380. There is no magical line of death that if the bullet reaches, you die. In the end it is just a balance of the size of gun, cartridge, amount of expansion, and penetration. I don't think Speer should have to test their .32 or .380 ammo and if it fails to meet some arbitrary line they pull it off the shelves. I also don't think they are misleading consumers by marketing a round as self-defense if it only penetrates 10 inches.

Additionally, I know this wasn't meant to be a FMJ vs JHP thread, but that is often what it boils down to. That, or JHP #1 expands less, but penetrates more than JHP #2. I like to think of it from a perspective of potential scenarios and advantages of each.

1. You miss. Advantage neither (or maybe JHP that may have less chance of ricochet).
2. You miss COM entirely and hit soft tissue in a non-(immediately)-life-threatening body part. Either way you get a through-shot. Advantage JHP, since chances are, it will hurt more, (think psychological stop), leave a bigger exit hole, and have less velocity on the other side to hopefully do less damage.
3. You hit COM, adequate penetration, but just barely miss a vital like the heart. Advantage JHP because it will hurt more, leave a bigger wound channel, and the expanded diameter may knick an artery or something important.
4. You hit COM, perfect trajectory for a heart-hit, but since you had to shoot through a wall or door, the JHP expanded and did not penetrate enough, but the FMJ did penetrate enough and hit the vital. Advantage: FMJ.
5. You hit COM, perfect trajectory for a vital-hit, and you did not have to shoot through anything, so both JHP and FMJ work fine. Advantage: neither.

As you can see, only one scenario favors the FMJ. People get so caught up in the idea that they will have to shoot through something, and assume the most likely scenario is the bullet stops 1" short of the heart, they never worry about the other, more likely, scenarios.

Again, it all comes to balancing the variables and finding something you are comfortable with. Is a round that expands to 0.45" and penetrates 12.5" fine, and a round that expands to 0.6" and penetrates 11.5" is insufficient? I don't think so. Or what about a .355" round that doesn't expand at all and penetrates 16"? that's for everyone to decide for themselves.

Guess we are dredging this up again? LOVE first posters.

To all of you "bullets that pass all the way through are wasted energy" believers;
CODSWALLOP.

Take any two bullets, that are of the same diameter and weight. Assume They expand to the same diameter when entering the tissue at the same place in the tissue, and the projectiles retain the same wait. One is moving fast enough to make it through the "target" the other is not. The faster round will almost always be more effective. (there is an exception to this which is why I use the word "almost", I have read about a velocity threshhold where hard cast bullets with large meplats do less damage than the same bullet going slower which is negated by turning them into hollow points, but that is another subject all together)

Here's why, and you don't need energy and mass formulas to prove it, just common sense. The answer is partially Hydrostatic shock. The faster a bullet is moving, the more Hydrostatic shock it will deliver. The faster projectile will move the flesh around it at a higher velocity, which means it will move the flesh more. That means the temporary wound channel will be larger, and the permanent wound channel as well, as the energy rips the flesh.
Consider a rock falling into water. It will splash. Now Double the velocity of the rock and do it again. It will make a larger splash. The same can be seen with meteorites striking the earth. Take two rocks of the same size, drop one from your roof and the other from space. Which one makes a bigger crater or causes more damage? And last comparison; If you have ever seen a 7.62x39 hitting water jugs, and a 308 hitting the same water jugs, the difference in the resulting water works is well, the 308 is quite spectacular, the 7.62x39, is not so much.
Penetration really has nothing to do with this aspect of the argument, but is certainly an added bonus. If that bullet is moving farther into the target, more of the target will be damaged, plain and simple.
If someone is worried about hitting bystanders, so be it, it's a valid concern to be sure. Don't think that having it stop in the flesh makes it more effective, that is foolish.

Liability - there's a personal injury attorney on every corner.

The original question: Why do manufacturers make underpenetrating loads for defense?

The answer is the same no matter about what thing you ask it: they make it because they discovered it was profitable to make and sell.

If an ammo/bullet maker believed he could make a profit selling rounds consisting of worn-out brass and pre-chewed Juicy Fruit, he would do it, and why not? All the discussion of the science behind various aspects of bullet design, velocities, etc. is interesting to a point, but it overreaches the actual question.

Why does the hotdog vendor sell hotdogs? It's not for health reasons, and it's not for nostalgia; it's because he can buy, heat, and present a hotdog at a cost of .23 and sell it for 1.75, and he needs no other reason.

I wish the only concern innocents in a shooting was overpenetration.

Invariably, they are hit by flying bullets that never hit the perp in the first place.

I think security applications in heavily populated areas (such as a casino, mall, travel terminal) have different factors from the home defense or personal defense scenario. If I was in the situation where I knew there would be hundreds of bystanders, I would want something that stops inside the assailant.

Click to expand...

In my current house, any round that exited an assailant in my hallway and that was capable of penetrating an exterior wall would travel about 25 yards and enter a mobile home next door. So, no, I most assuredly do NOT want a HD round that will penetrate 18" in gelatin, and I avoid them. If you prefer very deep penetration, that's your choice, and there are plenty of loads on the market that meet your criteria. I'm glad there are also loads on the market that meet mine; that is the beauty of a free market, after all.

Think the short answer is that some of us are not zombie hunting milita guys who like to believe they are preparing for a full scale military assault on their humble home. Like others have said on the thread, don't like them, then don't buy them. Those of us who have decided that we aren't wanting a round to penetrate thru 3 walls and lodge in the back seat of our neighbors car that is sitting in his garage, don't think we are making a compromise when we purchase reduced recoil rounds or select a HD weapon in a caliber that likely won't exit a bad guy.

The FBI really gave a lot of gun guys a good handle to use to smear certain weapons and ammo. All this use to be limited to not relying on a 25auto or 32S&W that are famous for being anemic. Then it was the 38 and the 380. Amazingly the 38 and 380 are making a comeback.

Actually, after shooting through drywall, the JHP will clog up but fail to expand (hydraulic pressure is usually what drives the expansion). Hence, it will be clogged up, won't expand in the human target, and act like a FMJ zipping through.

Click to expand...

Never specified type of wall. It could be a car door, glass, anything. My only point was it loses some steam on its way to the target. But you did just make my point for me that, if the JHP doesn't expand, it is effectively an FMJ. So that negates some of the FMJ's advantage.

No, but in a situation where one bullet stopped short of vitals...you see where I'm going with this.

Click to expand...

I hear ya, and it is always a concern. Whenever possible I carry a bigger better cartridge, but sometimes I may be carrying something in the gray area of less penetration. Again, not "under-penetration." I just don't get why the "stop short" concern is always at the forefront, when, as I showed, there are a lot of other possibilities. IMO it is actually way more likely that you will miss a vital than have a bullet on an otherwise-perfect trajectory stop short. In many instances, for many people, a lighter-recoiling round with greater expansion and less penetration may be better for someone.

The Miami shooting is one very infamous instance where allegedly a bullet stopped about an inch short, and if only they had used a more powerful round, the perp would have been stopped much sooner, avoiding more tragic loss of life. But, of all the lessons we can take away from that shootout, I think "such and such round or x-inches penetration is inadequate" is the least important. Shot placement, tactical/situational awareness, sustained suppressive fire, and not bringing pistols to a rifle fight, I think are all much more important lessons.

5) Even a .223 or .30 cal rifle round will only make a hole that size unless it tumbles. (It has to encounter a lot of tissue to start tumbling.)

Click to expand...

No, it does not have to encounter a lot of tissue to start tumbling; all that is required is to destabilize the bullet. The action that causes this is the change in density from air to human tissue. When a .223 round hits human tissue at self defense ranges, it will be traveling over 2,700 fps.

The center of mass of the bullet will be slightly behind its longitudinal center, and this means that the front of the bullet is lighter. When the round impacts human tissue, the immediate change in density will cause the bullet to slow and because the front of the bullet will slow at a faster rate because. This is what causes yawing, the rear of the bullet will end up going faster than the front and will "tumble" end over end once this destabilization occurs.