History of using layers of denim in balistic testing?

[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]

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.

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.