Why do manufacturers make underpenetrating loads for defense?

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

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.



ETA: Forget my answer, Sam wins again...

And, because for every thread out there asking for loads that meet the minimum, there are two worried about "overpenetration."

Hard to tell which thing each shopper might be worried about so it's best to make both.

I think that 12"+ "rule" and the 10mm and .40 came from the Florida fiasco. Gotta blame something.

Because they don`t want to over penetrate & poke holes in bystanders.............

In the casino business over penetration leads to multiple civil suits, in the case where a projectile would penetrate thru one body (the perpetrator) and strike a second innocent bystander. I prefer a light projectile that will expend it's energy in the intended target. I also use this round as my home defense load. I prefer Corbon 135 grain in the .40 S&W and Corbon in the 110 grain in the .38 Spl. I also use the 185 grain Corbon in my .45 ACP. My wife uses Hornady Critical Defense 90 grain in her .380 auto.

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.

Click to expand...

Well that's the theory, but bullets IRL don't always behave as they are supposed to. They veer off, get lost in fat layers, get mired down by layers of clothing, and lose velocity before reaching anything vital. That's why you'll find many reports of suspects surviving many hits from handgun rounds from 9x19's to .45 ACP.

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. It also helps ensure that the round has enough power to continue penetrating straight and not lose juice and start to veer off. With the right bullet design, it also dramatically increases the lethality by creating a much larger exit wound.

These are all among the reasons why through-and-through penetration is seen as a positive good for hunting. And there is no question that a round powerful enough to penetrate straight, expand, and exit, is far superior at stopping a threat than one which enters, slows fast and stops.

However, there are some tradeoffs involved. Handguns are generally weak and underpowered. To make a round powerful enough to offer the full expansion and through-and-through penetration, you have to amp up the charge and that means more recoil. We're really talking about bullets in the range of a .357 Maximum or .44 Magnum, and that's just not terribly practical for real life use in a CCW platform.

Ironically, and ingeniously, the handgun bullet makers have turned the disadvantage into an advantage. They've turned the *MINIMUM* penetration depth figures into an *IDEAL* penetration depth. Which it was never supposed to be.

will expend it's energy in the intended target

Click to expand...

This is an example of how successful the marketing scheme has been. In reality, that's just sales spin. "Expending its energy in the target" is really admitting the BULLET STOPS MID-WAY. And a bullet that stops is a bullet that stops working.

Overpenetration is another way they've whipped up fear to increase sales. While it's happened before, it's vastly more likely that a bystander will be injured by a CLEAN MISS than a round that overpenetrates. Furthermore it's easy to control the performance of the round IF you have sufficient velocity. So you can ensure through bullet design that upon exploding out in the exit wound, the bullet will be in pieces, but only if you have the energy to play with. A slowing, stopping bullet won't expand let alone explode. Which of course favors use of the AR carbine or similar long gun over any handgun. You minimize danger to third parties by reducing total rounds fired and increasing the effectiveness of the rounds you do fire.

Personally, I've gone back to good old-fashioned soft lead projectiles for handgun use. They penetrate better than most higher-tech rounds and have a reasonable track record. They're still very underpowered and far inferior to a long gun, but for emergency purposes they're about the best that can be done.

do they go by a different requirement?

Click to expand...

There is actually no "requirement" they must meet.

It is called a free market.

skribs said:

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."

Click to expand...

I think Sam hit the nail on this one... the less effective bullets are sold to satisfy the desires of a market segment that is terrified by the idea of over-penetration. But, reality is that a bullet that penetrates deeply enough to do its job is going to be a bullet that can also penetrate wall board and other such objects (as such, hitting your target does minimize this risk a bit).

allaroundhunter said:

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

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.

Click to expand...

Except that the 12-18" penetration goal is AFTER the bullet has struck intermediate barriers such as windshield glass, etc (in other words, in LE we aren't looking for a deeper penetrating bullet because of these barriers, we are looking for that much penetration even IF we penetrate those barriers). As such, the only difference in what law enforcement may require is that their bullet still needs to maintain that level of effectiveness AFTER striking those barriers. The goal on-target is still 12-18" of penetration in calibrated (I believe 10%) ballistic gelatin.

Bullets do funny things. Sometimes a bullet will get deformed/clogged after going through a barrier (be it clothing, wall board, windshield glass, etc), and will then fail to expand, thereby penetrating more deeply. Other times a bullet may come apart and fail to penetrate as expected after striking an intermediate barrier (my department switched our rifle ammo after observing this trend during shots through barriers -- I was at the workshop myself, and wasn't thrilled with seeing 7" penetration from a .223).

As an example of why the 12-18" of penetration in calibrated ballistic gelatin guideline is used, consider the following shot:

An adversary that weighs 350 lbs is facing you from the side. The only shot you have toward the vitals involves shooting through the arm, before hitting the torso itself. First, you may very well need at least 12 inches of penetration on such a shot against a person who's that big, especially if you have to shoot through an arm to get to the vitals. Secondarily, you will quite possibly hit bone. The 12-18" is based purely on gelatin, whereas bone will most certainly change the real world performance.

In our wound ballistics workshop (which was put on by ATK) we conducted the tests in a standardized manner. The intermediate barriers consisted of things like windshield glass, wall board, light clothing, and heavy clothing, all per the FBI protocol. But, we also shot the gelatin without going through an intermediate barrier. The goal in each test was to land in the 12-18" penetration range.

loose noose said:

I prefer a light projectile that will expend it's energy in the intended target.

Click to expand...

The whole concept of "energy transfer" with a bullet is meaningless. Don't get me wrong, I know you aren't the one who pioneered this idea. It has been talked about at gun store counters and in the halls of gun shows for years. Some companies even market to the idea. Put as simply as I can say it, the size and depth of the hole made by the bullet is what matters here (these things can be determined by the velocity of the bullet, the size of the bullet, the expansion of the bullet, and how the bullet stays together after making contact).

A bullet that stops short after a hit simply stops. It doesn't deliver any more practical energy to the subject than the bullet that zips on through. The idea of "knock down power" is great for marketing, but a poor thing to bet your life on. Simply put, a bullet doesn't just knock you down.

There is actually no "requirement" they must meet.

Click to expand...

There you go.

The FBI came up with a standard for their agents, given the type of encounters they have. Most LE departments don't have the resources of the FBI, and said "close enough--we'll have what they're having."

To the extent that your encounter differs from the average FBI one, you might want a different ammo standard.

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.

The whole concept of "energy transfer" with a bullet is meaningless.

Click to expand...

Well, that's not strictly accurate. Everyone (I think) agrees that once energy levels reach those of rifle rounds, temporary cavitation (driven by velocity and energy transfer) becomes an important wounding mechanism, especially if coupled with bullet fragmentation.

Part of the disagreement on handgun energy importance stems from the phenomenon of non-fatal stops. Statistics seem to indicate that most persons shot with handguns survive, suggesting the attackers among those survivors stopped before being wounded in a vital organ and bleeding out (or receiving a fatal CNS hit). We also have the anecdotal evidence that low-energy-deposition rounds (like the old .38 Special 158 gr RNL) were ineffective at ending fights; while high-energy (like the Illinois State Police 9mm+P+) rounds were anecdotally very effective.

So, if one focuses on the idea that a bullet must under all circumstances penetrate to a vital structure to produce a "dependable" stop, you may decide that energy doesn't matter. Even if it seems that striking a vital structure is not necessary to end the majority of gun fights, or if there is anecdotal evidence that high energy handgun rounds stop fights better than low energy ones.

Good news: modern loads tend to give us both good penetration and good energy deposition, so you don't have to choose. We still have room to argue, though, about whether 11 inches of penetration is actually worse than 12 inches; and whether 14 is better than 12. Mostly because we have no good data to show us whether an extra two or three inches of penetration make a significant fight-stopping difference.

low-energy-deposition

Click to expand...

What energy are you talking about? It's not as if a bullet that stops mid way sends some kind of shockwave in *front* of it after stopping. The round simply loses its juice and ceases to do any further damage. Whether or not that damage is sufficient depends on what tissues it has destroyed up to that point.

I've never seen support for the notion that the raw foot pounds of the round, absent actual tissue damage, serve any role at all. Of course if you have enough energy you can use it to expand hollow points and increase tissue damage. But a lot of handgun rounds don't have enough, and end up with HP's that act like an air brake.

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

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.

Click to expand...

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.

Bad guys don't stand still with bulls-eyes painted on their chests while you shoot them. They are ducking, running, squatting, hiding behind barriers, turned to one side and making it as difficult as possible for you or a LE officer to hit them. Your bullet may have to penetrate a bicep muscle and 3 layers of clothing before even striking the chest from a side shot.

Well as someone who has been hit by a wayward bullet that over penetrated I can tell you when I carry SD loads it is a JHP and I don't want nor need more than 12" of penetration. Besides a fmj round which will over penetrate doesn't stop as quickly as one that expands when it hits soft tissue. Oh and I was hit by a 38 after it passed through anothers upper body then a table 50' from the shooting and lodged against the bone in my forearm.

What energy are you talking about?

Click to expand...

The bullet's kinetic energy, which (if the bullet stays in the body) is expended by bullet deformation; direct tissue injury; tissue displacement and tearing (at higher energies); heat; and a small amount of imparted kinetic impulse to the body.

I've never seen support for the notion that the raw foot pounds of the round, absent actual tissue damage, serve any role at all.

Click to expand...

This is a little like saying you've never seen evidence that a bullet, absent actual tissue damage, serves any role at all. At rifle energy levels, tissue tearing (caused by cavitation) can be the predominant mechanism of injury.

And then of course, there is the anecdotal evidence of the ISP 9mm vs the NYPD .38 RNL. To the extent that there is "no evidence" that energy makes a difference, there will also be "no evidence" that it does not; so it will boil down to which assumption you prefer.

Civilians are just as likely to have to penetrate barriers as LE in a shooting.

Click to expand...

Is there data that supports your opinion?

The FBI understandably (given their routine need to approach vehicles) specified ammo tests using automobile glass and sheet metal. I think my likelihood of shooting through those barriers is lower than theirs, but YMMV.

Why do manufacturers make underpenetrating loads for defense?

Click to expand...

I don't think they do it on purpose it's just they're in the business to sell cartridges and the FMJ doesn't offer the marketable hype jhp does.

the best sales pitch is to create a problem then sell the solution.

you could always carry FMJ if penetration is a concern, I do.

huntsman said:

I don't think they do it on purpose it's just they're in the business to sell cartridges and the FMJ doesn't offer the marketable hype jhp does.

the best sales pitch is to create a problem then sell the solution.

you could always carry FMJ if penetration is a concern, I do.

Click to expand...

Have you ever shot a rabbit or deer? Never mind.

They could get better penetration out of a heavier bullet using otherwise the same bullet design.

Click to expand...

And it would cost them more in lead and copper and recoil more. They've made a DRAWBACK into an ASSET. It's brilliant, really. It's the same as selling a car that can't go over 35 MPH as a state-of-the-art marvel designed to keep you extra safe.

I love reading all the experts in physics here.

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.

It's not that the bullet "stops working", or that someone is being "sold" something, or the manufacturers are trying to save .0007 cents per bullet. It's simply that some people disagree with your "opinion". Get over it and let people use what they want.

Certaindeaf said:

Have you ever shot a rabbit or deer? Never mind.

Click to expand...

lots why??

loosedhorse said:

Well, that's not strictly accurate. Everyone (I think) agrees that once energy levels reach those of rifle rounds, temporary cavitation (driven by velocity and energy transfer) becomes an important wounding mechanism, especially if coupled with bullet fragmentation.

Click to expand...

Yes, indeed. But that's not the "energy transfer" that people are speaking of when they talk about the advantage of having a bullet stay in the body and "dump all of its energy", rather than "passing right through and doing nothing".

High velocity rifles are truly devastating when compared to typical defensive pistols. Yes, they are higher energy. But, whether that bullet stops in the body or goes on through is largely irrelevant, aside from considering what structures are damaged by that bullet. 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).

Skribs said:

Huntsman, I'm not talking FMJ vs. JHP. I'm talking a light bullet that isn't designed to be hot (or a really light bullet in +P) that penetrates less than 12 inches. They could get better penetration out of a heavier bullet using otherwise the same bullet design.

Click to expand...

when the discussion of penetration comes up it's usually FMJ vs JHP my bad, I don’t believe there’s much difference between a 185gr or 230gr jhp in my .45acp.

Maybe I'm missing something or is your issue caliber specific?

I have some of the new whiz-bang SD stuff but I'd never buy frangable and I'm not running out to spend money on Critical defense

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

Click to expand...

Actually, you do gain "energy transfer." If a bullet exits, then whatever kinetic energy it has on exit did not get transfered to the target. Therefore--assuming both bullets initially had the same kinetic energy--tissue was stretched (and torn) by temporary cavitation less by the bullet that exited with some residual kinetic energy than by the bullet that "dumped" all its energy into tissue cavitation.

For pistols, we're dealing with two unanswered questions. I mean unanswered experimentally, since we don't have actual, carefully collected data. Both questions are answered--in all sorts of different ways--by various competing theories. Unfortunately, without the data, we can't be sure which competing theories to discard.

The two unanswered questions are: is greater energy transfer (at handgun energy levels) an important factor in stopping most attackers; and, is the difference between projectiles that penetrate 11, 12 or 14+ inches actually important to private citizen SD gunfights?

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).

Click to expand...

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