History of using layers of denim in balistic testing?

[JustOneGun]

I only know enough to be dangerous when it comes to ballistic testing criteria and how it changes bullet design for good or bad. Knowingly, I am asking for a very simplified answer in a complex field.

While working in aviation I came to understand the government selects many materials in order to standardize tests for repeatability and availability of said material. Manufacturers then tailor their product to maximize the test. This may or may not maximize performance given the above tradeoffs of standardization when compared to the real world.

With this in mind I have two questions:

1. Is there real world morgue and ER results that settle the test on a certain number layers of denim? How scientific was it?

2. All things being equal and given the design of the tests, do scientists expect to see a variety of expansion and penetration depths between the minimum and maximum dependent upon how much the individual bullet clogs? If not expecting a proportional result, what are they expecting?

[Chuck Haggard]

http://www.firearmstactical.com/tacticalbriefs/2006/04/02/0604-02a.htm

http://www.ar15.com/ammo/project/Fackler_Articles/winchester_9mm.pdf

In the FWIW department, almost every 124gr +P Gold Dot that I have seen that has struck a bad guy in one of our OISs looks exactly like those recovered from the 4LD gel testing.

[JustOneGun]

Chuck,

Thanks for the links. I have read the article quoting MacPherson but every article I find is lacking the last three pages where it discusses how the 4 layers was determined. It seems to be MIA. (: Is it in one of his books and if so which one?

What I did read in the article made me even more curious. MacPherson states that in CHP's shootings a very small percentage of the bullets failed to expand. Was he basing his conclusions off a small percentage of failures in one brand of bullet?

Through my ignorance of ballistic testing I'm sure there is something obvious I'm overlooking.

[Chuck Haggard]

The 4LD test was used as a worst case scenario test, since "heavy clothing" meant a lot of different things to different people, and the denim would be easy for everybody to duplicate. Every bullet that I have seen that does well on the 4LD test has done well on the street.

Previous to us using the Gold Dot we used the Hydrashock, and saw more than a small sample of bullets that failed to expand through clothing in our OISs.

[DocGKR]

MacPherson D: "Improved Handgun Ammunition". Wound Ballistic Review, 3(3):12-21, 1998.

[JustOneGun]

Chuck thanks for the input, I was wondering if there was a problem prior to the test and a subsequent reduction of that problem. I do understand the need for standardization of tests and was not questioning the need for it. I don't believe that I will get an answer as to how 4 layers was determined to be better than 2, 3 or 5?

My initial question came about because if the 4 layers was picked as an extreme test that is actually overkill, then in trying to pass that test are manufactures having to do something to a bullet design that perhaps makes it not expand as large as possible given a more realistic test criteria?

So having a test that is a more than what is seen in reality is a good idea. Having a test that is way overboard might actually hinder performance. I am not suggesting that is what is going on. I don't have enough expertise and experience when it comes to ballistics. I was just curious as to the history of the tests development and how it changed bullet expansion, cost, higher speed impeding recoil recovery, etc.

[Sigfan26]

The Canadian tuxedo was more popular in the early 90's than today. While many consider 4ld to be overkill, if something kicks ass in that, it's gonna rock in almost any environment.

[JustOneGun]

Thanks Doc, I read that one but have been unable to find a copy that actually has the history of development. The closest I got was, they experimented and determined 4 layers was best.

So they experimented with different materials and found denim clogged the best. Then they experimented with different brand rounds or just one round that passed fbi tests but had shown to fail in the human body? Then with these bullets they kept adding layers until they replicated the failures seen in the body or a slightly higher percentage or did they keep adding layers until they all failed? The difference could be important.

I was just pondering the history of the test.

[JustOneGun]

The Canadian tuxedo was more popular in the early 90's than today. While many consider 4ld to be overkill, if something kicks ass in that, it's gonna rock in almost any environment.

That may or may not be true.

Back in the '80's the Navy E-2 aircraft had an ashtray that cost hundreds of dollars (I think it was either $400 or $800 one was the army's hammer) It kicked ass on a lot of difficult and elaborate tests that the Navy required. There were two important things concerning that ashtray. 1. It was just like the one I made my dad in high school sheet metal shop. It cost me like $10 and 45 minutes to make. 2. When the planes got to the squadrons we took the ashtrays out and put them in a closet. Smoking in a plane full of electronics is not the best idea. Go figure.

So we wasted a lot of money and time for a product we didn't want and with tests that were overkill. That overkill drove up the cost.

[Sigfan26]

That may or may not be true.

Back in the '80's the Navy E-2 aircraft had an ashtray that cost hundreds of dollars (I think it was either $400 or $800 one was the army's hammer) It kicked ass on a lot of difficult and elaborate tests that the Navy required. There were two important things concerning that ashtray. 1. It was just like the one I made my dad in high school sheet metal shop. It cost me like $10 and 45 minutes to make. 2. When the planes got to the squadrons we took the ashtrays out and put them in a closet. Smoking in a plane full of electronics is not the best idea. Go figure.

So we wasted a lot of money and time for a product we didn't want and with tests that were overkill. That overkill drove up the cost.

Comparing bullets and ashtrays is like comparing Apples and hamsters... Who doesn't want a better performing bullet?

[JustOneGun]

Comparing bullets and ashtrays is like comparing Apples and hamsters... Who doesn't want a better performing bullet?

The point was that the ashtray performed exceptionally well per the test. Yet the outcome was idiotic. Now I have no idea if what I asked about ballistics it true. I just don't have the experience to say one way or the other. Hence asking the question.

To help you understand my point: let's say that if I made a bullet to pass the 4 layer test and it worked well and expanded to .6 and 14inch penetration. What if I told you that I could make a bullet expand .7 with 14inches of penetration but it will only pass a test of say 3 layers of denim. It fails the 4 layer test. If the 4 layer test is overkill and 3 layer test will not result in poor performance in the human target, the fact that your bullet kicked ass on the 4 layer test did not result in the best performing bullet?

Again, I have no idea if that is even possible. Bullet construction just might not work that way. It never hurts to ask.

The ashtray example happens everyday in the gun world. I believe asking questions about base assumptions helps me put idea into perspective. And every so often someone asks a question that changes how we do things. If we stick around long enough we all tend to look back and say, "I can't believe I used to think that was cutting edge."

[Sigfan26]

The point was that the ashtray performed exceptionally well per the test. Yet the outcome was idiotic. Now I have no idea if what I asked about ballistics it true. I just don't have the experience to say one way or the other. Hence asking the question.

To help you understand my point: let's say that if I made a bullet to pass the 4 layer test and it worked well and expanded to .6 and 14inch penetration. What if I told you that I could make a bullet expand .7 with 14inches of penetration but it will only pass a test of say 3 layers of denim. It fails the 4 layer test. If the 4 layer test is overkill and 3 layer test will not result in poor performance in the human target, the fact that your bullet kicked ass on the 4 layer test did not result in the best performing bullet?

Again, I have no idea if that is even possible. Bullet construction just might not work that way. It never hurts to ask.

The ashtray example happens everyday in the gun world. I believe asking questions about base assumptions helps me put idea into perspective. And every so often someone asks a question that changes how we do things. If we stick around long enough we all tend to look back and say, "I can't believe I used to think that was cutting edge."

Issue with the ashtray is that you don't need an ashtray period. While you may find some rounds that do not meet all test criteria that perform well in actual shootings (Federal 9BPLE), rarely Will you find bullets that meet all test criteria and do not do well in actual shootings. Anecdotal data is not testable/repeatable data.

[JustOneGun]

Issue with the ashtray is that you don't need an ashtray period. While you may find some rounds that do not meet all test criteria that perform well in actual shootings (Federal 9BPLE), rarely Will you find bullets that meet all test criteria and do not do well in actual shootings. Anecdotal data is not testable/repeatable data.

While I agree with you, you are missing the point of the entire thread. You are talking about finding a well performing round that meets the test criteria. If our criteria is flawed then you have garbage in and garbage out? When you consider how manufacturers cater to testing, our selection of ammunition might not be as broad or well performing as it might otherwise be due to accepting a poor test criteria. What I read about the test didn't make sense so I was curious about how the selection was made, that's all.

[Sigfan26]

While I agree with you, you are missing the point of the entire thread. You are talking about finding a well performing round that meets the test criteria. If our criteria is flawed then you have garbage in and garbage out? When you consider how manufacturers cater to testing, our selection of ammunition might not be as broad or well performing as it might otherwise be due to accepting a poor test criteria. What I read about the test didn't make sense so I was curious about how the selection was made, that's all.

I get what you're saying now. My guess on the criteria, fashion of the late 80s/early 90s. Denim jackets and shirts were normal (1989, 4ld was likely to be encountered). Today, baggy and heavy leather jackets (many times filled with a liner such as down) over heavy cotton polo are common. While the 4ld may be dated, the worst case test parameter(clothing wise) is an easily tested constant.

[Sigfan26]

http://tapatalk.imageshack.com/v2/14/10/09/52483412475b7850c7884638bf3565cd.jpg
4Ld example

[DocGKR]

Perhaps I am a bit confused, but it seems to me that the answers to the majority of your questions are included in the paper I referenced above. For example:


"Since cloth seemed to be the most practical test soft barrier, several kinds of cloth were purchased and tested to determine what characteristics had the largest effect on the ammunition brands provided."


"CHP .40 S&W issue ammunition (past and present) and a variety of other ammunition in .40 S&W and .45ACP calibers was used in these investigative tests. This testing showed that the effect of the cloth barriers did not seem to be ammunition brand specific; i.e., if a selected cloth barrier presented expansion problems for one brand and caliber, it presented problems for all brands in either caliber."


"The conclusion of these investigative tests was that the denim alone seemed to provide a stressing but reasonable test......The number of layers of denim penetrated had been a variable in the investigation; not surprisingly, more layers caused greater expansion problems. Four layers of this heavy denim was adopted as the standard for future testing (and became the final protocol standard). This standard does not represent any specific clothing; it was selected to provide a standardized, inexpensive, and precisely defined soft barrier requirement designed to force robust JHP bullet designs; i.e., designs that expand much more reliably against the soft barriers most common in law enforcement shootings."


"There is not reason to believe that ammunition expansion performance will be sensitive to small variations in the denim, and good reason to believe that it will not. Four layers of denim is a convenient standard because this can be obtained simply by folding the cloth twice; either 3 or 5 layers does not appear to produce dramatically different results."

Having personally been at the CHP Academy performing wound ballistic testing from 1992-2000, my summary of the events in question relates that a unacceptable number of failures of LE JHP duty handgun ammunition in OIS incidents was noted--these were predominately failures to expand in ammunition that had previously performed well in bare gelatin and "heavy clothing" test protocols. To devise a more accurate test methodology to assess the robust expansion capability of service caliber JHP bullets, variety of soft barrier materials and configurations were tested against a several .40 and .45 caliber JHP duty loads. After settling on heavy denim (16 oz per sq yd) as the best soft material for testing and assessing it's performance with various thicknesses of denim, it was determined that four layers of denim (4LD) provided the most accurate and efficient replication of bullet failures that had been noted in OIS incidents. One of the senior engineers at a very respected ammunition manufacturer has commented that handgun bullets that do well in 4LD testing have invariably worked well in actual OIS incidents. Most handgun bullets recovered from human tissue in surgery or at autopsy tend to look like those same type of projectiles after 4LD testing.

[Chuck Haggard]

Most handgun bullets recovered from human tissue in surgery or at autopsy tend to look like those same type of projectiles after 4LD testing.

This is what jumped out at me in my observations of recovered bullets from our OISs.

Specifically, if almost all of your real world bullets look and perform exactly like the bullets in the 4LD test event then I think it strongly validates that test.

[MGW]

Interesting stuff. Thanks for sharing Chuck and Doc.

[JustOneGun]

Perhaps I am a bit confused, but it seems to me that the answers to the majority of your questions are included in the paper I referenced above. For example:

Having personally been at the CHP Academy performing wound ballistic testing from 1992-2000, my summary of the events in question relates that a unacceptable number of failures of LE JHP duty handgun ammunition in OIS incidents was noted--these were predominately failures to expand in ammunition that had previously performed well in bare gelatin and "heavy clothing" test protocols. To devise a more accurate test methodology to assess the robust expansion capability of service caliber JHP bullets, variety of soft barrier materials and configurations were tested against a several .40 and .45 caliber JHP duty loads. After settling on heavy denim (16 oz per sq yd) as the best soft material for testing and assessing it's performance with various thicknesses of denim, it was determined that four layers of denim (4LD) provided the most accurate and efficient replication of bullet failures that had been noted in OIS incidents. One of the senior engineers at a very respected ammunition manufacturer has commented that handgun bullets that do well in 4LD testing have invariably worked well in actual OIS incidents. Most handgun bullets recovered from human tissue in surgery or at autopsy tend to look like those same type of projectiles after 4LD testing.

Doc thanks for taking the time to reply, I appreciate it.

You are not confused, I was. As I mentioned earlier I don't have and can't find what you site. The webpage for me to order it IWBA is defunct. All I was reading were excerpts from it. I knew I was probably missing something obvious but just didn't know what it was. The summary of the test history and excerpts your provided did answer most of my questions. Again, thank you. Perhaps my power to google needs work. And the other questions you didn't address I did find later in old articles referencing IWBA.

Where you able to put a percentage, even loosely, on the failures before the improved test and the percentage of failures after?

Some of the old IWBA stuff mentioned the fbi's resistance to changing the protocol of their tests. Do you know why they felt it wasn't necessary? Or was it they simply wanted to produce a high priced ashtray using their tests?

And FYI.... I should get brownie points for repeatedly refusing SigFan's request to turn this into an "it's realistic to have to shoot through 4 layers of denim" taunts. :D

Again, thank you guys for taking the time.

[DocGKR]

i don't recall the exact percentage of plugging failures off the top of my head (as a rough guess perhaps 25-35% of projectiles showed evidence of plugging)--I can state with confidence that failures due to plugging were substantially less after adoption of robust expanding projectiles.

When SSA Buford Boone took over the FBI BRF he did institute appropriate changes in protocol and data reporting.

[Jeep]

This is what jumped out at me in my observations of recovered bullets from our OISs.

Specifically, if almost all of your real world bullets look and perform exactly like the bullets in the 4LD test event then I think it strongly validates that test.

One of the best recommendations for any test is that it works--ie it fairly accurately replicates the things in the real world for which you are testing. It sounds like the 4LD test does precisely that.

[John Hearne]

Some times you get lucky and your test ends up having a very high correlation with the real world. The "big thing" is that the correlation is strong with the real world. If we could a higher correlation by shooting bullets into Breyer's chocolate ice cream then I'd care about the ice cream test.

[Hambo]

If we could a higher correlation by shooting bullets into Breyer's chocolate ice cream then I'd care about the ice cream test.

That wouldn't be a test, it would be a crime against humanity.

[dano1200r]

All the head shots I've seen make it a moot point if poa is good. But to the op: I'd recommend doing your own test for the way people dress in your part of the country.
Where I live in FL, I don't give alot of weight to the fbi test.

[Chuck Haggard]

Where I live in FL, I don't give alot of weight to the fbi test.

Why not?

The incident that started the FBI down the path towards modern ammo testing happened in Miami.

Just sayin.

[Jeep]

Why not?

The incident that started the FBI down the path towards modern ammo testing happened in Miami.

Just sayin.

Probably because they want to mimic what people are actually wearing in Miami. So, I suppose the real question for Miami Beach itself, is whether one layer of either (1) premium fair-trade, organically grown cotton or (2) lycra will have a much different effect on a modern hollow point than the standard 4LD?

My guess is that it won't, and it will end up penetrating around the same amount of gelatin with the bullet looking pretty much the same.

The tests might cost a bit more, however, given the cost of premium fair-trade organically grown cotton t-shirts.

[DocGKR]

The 4LD test is NOT designed to simulate any type of clothing--it is simply an engineering test to assess the ability of a handgun projectile to resist plugging and robustly expand.

[Chuck Haggard]

The 4LD test is NOT designed to simulate any type of clothing--it is simply an engineering test to assess the ability of a handgun projectile to resist plugging and robustly expand.


Which is likely why almost all of the no clothing being hit shots in our OISs still resulted in bullets that look like they were pulled from the 4LD testing.

[Jeep]

The 4LD test is NOT designed to simulate any type of clothing--it is simply an engineering test to assess the ability of a handgun projectile to resist plugging and robustly expand.

Doc: Not arguing with you at all and it is obvious that the test does a good job of replicating the real world, but didn't the original idea for the 4LD come from the fact that a lot of the old-time hollow points were observed to be clogging on clothing (as well as other materials)?

In other words, the resulting engineering test used a material that was known to clog hollow points.

Thus, it strikes me that if there was any reason to believe that my fanciful example of one layer of organic free-trade cotton would clog modern hollow points that wouldn't clog with 4LD then one might question the suitability of the engineering standard for the purpose at hand--ie: stopping actual people before they can hurt someone.

Of course, based on the information from people like you and Chuck, there is no reason to think that using a different type of fabric in the testing would change the results in a material way. 4LD works.

However, if hollow points routinely clogged on the clothes that people actually use but not on 4LD, I would think while the engineering standard would still be valid as an engineering standard used for comparison purposes, it would be far less useful as a predictor of how a bullet would likely perform in an actual shooting. One of the great things about the current test is that from all appearances it does both.

[DocGKR]

Uh, perhaps that is why different types of material and different thicknesses were tested until one (4LD) was found that correlated with real world events...

[Jeep]

Uh, perhaps that is why different types of material and different thicknesses were tested until one (4LD) was found that correlated with real world events...

Yes--which is why it seems to me to be more than just an engineering standard--it is an engineering standard developed after long testing, and it is used not only for comparison purposes but because it works as a very good predictor of real world results regardless of the actual clothing someone is wearing. (Which is why a different test is not necessary for Miami or Nome).

[JustOneGun]

Uh, perhaps that is why different types of material and different thicknesses were tested until one (4LD) was found that correlated with real world events...

During the test creation and since has there been any false negatives where a bullet worked very will in real world shootings but didn't do so well on the test? And if so did you/they isolate why the false negative happened (i.e. certain type or shape of bullet at a certain velocity)?

[DocGKR]

Nope--vast majority are just like the test. Keep in mind that with good shot placement, even a .380 FMJ works fine.

[JustOneGun]

Nope--vast majority are just like the test. Keep in mind that with good shot placement, even a .380 FMJ works fine.

You of course are correct about shot placement. I just was curious about this subject, that I don't know much about.

Can you recommend any in print books on the subject as an overview of testing and how modern bullets have been manipulated to meet the tests criteria?

[DocGKR]

Sadly, no such book exists on this arcane subject.

[Chuck Haggard]

Getting ahold of old copies of the IWBA journals, if you can find some, and looking through Firearms Tactical's site is my off the top suggestion.

[JustOneGun]

Getting ahold of old copies of the IWBA journals, if you can find some, and looking through Firearms Tactical's site is my off the top suggestion.

Finding them is next to impossible. The only book I found was Macpherson's and it is out of print and stuck in folks libraries. (:

[wrinkles]

Finding them is next to impossible. The only book I found was Macpherson's and it is out of print and stuck in folks libraries. (:

I was lucky to find a place selling new books for 35.00 a couple of years ago. They are sold out.

Kindle Edition Amazon.


http://i212.photobucket.com/albums/cc111/agalindo_sbc/bulletpenetration_zpsc922d8dc.jpg

[JustOneGun]

Man, I must be getting old. I looked there first and didn't see it. KIndle is real easy.

Thanks