Inconsistencies between gel types in ballistics testing

1
Recently came across a series of articles comparing the performance of FBI grade 10% calibrated ballistic gelatin to the clear ballistic gel used by Lucky Gunner and elsewhere for terminal ballistics comparisons. There'd been indications that the clear stuff wasn't as dense before, with a tendency to overstate penetration and understate expansion. Well, that's putting it mildly.

Three parts. Part 1 is the history, Part 2 is the test, Part 3 is the analysis.
https://www.police1.com/police-products ... Hw79F9s0a/
https://www.police1.com/police-products ... SxRFxBwTL/
https://www.police1.com/police-products ... 93TAd5o6J/
There were two significant findings from this test.

First, none of the factory fresh, clear synthetic blocks passed FBI calibration, despite the fact that the included warranty cards indicated they would. Each of the four new blocks had warranty cards that indicated that calibration BBs had penetrated 3.5 inches in sister samples from the same lot, but when we tested the blocks, we recorded BB penetrations ranging between 4.625” and 4.875”. Due to the elastic nature of the material, the BB would penetrate, then spring back to a final resting place that was short of the overall penetration depth (the same happens in organic gelatin). The FBI measures the overall penetration depth, but even the shorter resting distance of our calibration BBs ranged between 4.0” and 4.125” in the clear blocks, which is beyond the FBI’s acceptable maximum overall penetration of 3.74”.

Second, our test of six different 9mm cartridges from five different manufacturers indicated that bullets tend to under expand and over-penetrate in the clear synthetic gelatin, compared to 10% calibrated gelatin. There was an insignificant difference in retained weight between the two test mediums, with the bullets fired into the clear synthetic losing the smallest fraction of their weight.
Looking first at the bare gelatin results, on average, the sampled bullets penetrated 35.5% deeper into the clear synthetic product than they did in the organic, 10% calibrated gelatin, with a range between 34.4% (the 135+P Hornady Critical Duty) and 36.3% (the standard pressure, 124 grain Federal HST).

When we added the FBI heavy clothing layer in front, the bullets fired into the clear synthetic continued to penetrate deeper than they did in the organic gelatin, by a startling average of 48.1% for all the tested cartridges. The highest difference in penetration was 56.1% more in the clear synthetic than the organic (the standard pressure, 124 grain Federal HST), and the lowest difference was 38.2% more in the clear synthetic than the organic (the 135+P Hornady Critical Duty).

The percentages are fine, but to put things into better perspective, the 48.1% average increase in penetration for the six loads fired into the clear synthetic gelatin, covered in heavy clothing, represents a little more than 6” of extra penetration in the clear synthetic product, compared to the organic product.
Now, we're well aware of the fact that aim is more important than ammunition. What's worth noting is that they aren't even comfortable with a simple conversion factor between gel types, like "subtract 6" of penetration" to compare clear gel results to FBI standards.

There are other people testing with 10% gel - BrassFetcher comes to mind. It's a terrible website from a design perspective, but has some data and video.
https://www.brassfetcher.com/Handguns/Handguns.html

Re: Inconsistencies between gel types in ballistics testing

4
Brassfetcher actually has a report buried away doing an early test comparing the two gel types, but only saw ~2.5" difference in 9mm, and derived a formula for conversion from one type to the other. Went so far as to calculate drag forces, which I really appreciated. Didn't get the severe difference in calibration depth either. Course, BF got much worse results in .40 S&W.

Makes me wonder about changes in formulation - they mentioned that calibration was much closer to standard depths after remelting the blocks. Small inconsistencies in water content could explain a lot. I don't think this would make me reconsider my ammunition choices, but it would be nice to see manufacturers of defensive ammo post some calibrated penetration data on their website, if not the box. Data geeks gotta data.

Re: Inconsistencies between gel types in ballistics testing

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I have found lots of information on manufacturers websites. Look in the LE sections. Hornady had quite a bit, and I think Federal did. Don't know what's there now.

A good thing about the Lucky Gunner tests is that there are so many of them, you can compare them against each other. Since they're done in clear gel, with a fabric barrier, you can probably expect penetration to be deeper than in some other mediums. You could just look for about 18" penetration, with good expansion.

Another way to pick ammo, at least in 9mm, 40, and 45ACP, is to look at what police departments pick. They have access to all the data, and all the major USA companies compete for their business.

Re: Inconsistencies between gel types in ballistics testing

6
Rust wrote: Sun Feb 28, 2021 7:02 pm I have found lots of information on manufacturers websites. Look in the LE sections. Hornady had quite a bit, and I think Federal did. Don't know what's there now.

A good thing about the Lucky Gunner tests is that there are so many of them, you can compare them against each other. Since they're done in clear gel, with a fabric barrier, you can probably expect penetration to be deeper than in some other mediums. You could just look for about 18" penetration, with good expansion.

Another way to pick ammo, at least in 9mm, 40, and 45ACP, is to look at what police departments pick. They have access to all the data, and all the major USA companies compete for their business.
PDs don't make ammo purchases based on that data alone. Budgets and relationships matter.

Many PDs use Glocks because they get them really cheap, not because they are the best.
It is an unfortunate human failing that a full pocketbook often groans more loudly than an empty stomach.

- Franklin D. Roosevelt

Re: Inconsistencies between gel types in ballistics testing

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K9s wrote: Mon Mar 01, 2021 12:58 pm
Rust wrote: Sun Feb 28, 2021 7:02 pm I have found lots of information on manufacturers websites. Look in the LE sections. Hornady had quite a bit, and I think Federal did. Don't know what's there now.

A good thing about the Lucky Gunner tests is that there are so many of them, you can compare them against each other. Since they're done in clear gel, with a fabric barrier, you can probably expect penetration to be deeper than in some other mediums. You could just look for about 18" penetration, with good expansion.

Another way to pick ammo, at least in 9mm, 40, and 45ACP, is to look at what police departments pick. They have access to all the data, and all the major USA companies compete for their business.
PDs don't make ammo purchases based on that data alone. Budgets and relationships matter.

Many PDs use Glocks because they get them really cheap, not because they are the best.
It is whatever was the cheapest gets the contract or who gives the most moola to the person selecting the contract.
Facts do not cease to exist because they are ignored.-Huxley
"We can have democracy in this country, or we can have great wealth concentrated in the hands of a few, but we can't have both." ~ Louis Brandeis,

Re: Inconsistencies between gel types in ballistics testing

8
It depends on the department, small departments just buy what's reasonably priced and will typically accept the manufacturers test data.
Larger agencies who are a little more savvy will just take the test data, put it into a contract, and hold the supplier to that level of performance, leaving the option for independent testing at any time.

These days, it's pretty rare there are competitions based on independent performance evaluations.

The manufacturers have this well in hand now, and you really have to go well out of you way to get "bad" ammo. Bullet testing is interesting and educational, but hardly necessary anymore.
“I think there’s a right-wing conspiracy to promote the idea of a left-wing conspiracy”

Re: Inconsistencies between gel types in ballistics testing

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For target shooting, the only things that matters are accuracy and reliability. In that sense, you're absolutely right - it's all pretty good.

For hunting and self-defense, terminal ballistics considerations come into play, and that's where the gel tests are nice. Odds are that a fraction of an inch expansion or a couple inches difference in penetration won't significantly change the outcome of a hunt or a defensive shooting. It's nice to have ways to systematically compare, and useful for people who are considering defensive applications.

One of the things I liked about LG testing was the extensive, systematic compilation of many brands and calibers using a consistent methodology. Like the gel, their methods and data were transparent. It's great to get a sense of which rounds perform consistently, and which ones don't - but the clear gel was always a question. Some very well established brands had serious underexpansion / overpenetration issues in clear gel. Others do fine.

BF is systematic but never had the same breadth of coverage or consistency in presentation. He's detailed huge variability in penetration in traditional 10% porcine gel based on gel temperature. One of the things I found annoying about the link in the OP was that they didn't show their work. Can't look through their data to see if a conversion formula is reasonable without posting data. But BF did find that expansion was very consistent between gel types, even if penetration wasn't.

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