Many of the 9mm rounds that appear to have poor expansion when simply looking at the numbers is because they expanded so tremendously well that the petals then folded back over onto themselves, leaving a .49" diameter (as a common example).
Yet, some other 9mm rounds barely expanded at all or simply deformed, such as the Gold Dot 147gr...….whereas that round is universally regarded as a good performer in proper testing, even being one of the recommended loads by Dr Roberts.
And then you get into the 380s, and a round that is universally recognized as a shallow penetrator (90gr Gold Dot) not only penetrates to 11", but expands so rapidly that its petals fold back on itself.
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I am not a ballistician, but it seems abundantly clear to me that clear gel is not an appropriate test medium compared to the industry standard being used by people who do this for a scientific living, not a blog living. It's clearly not something where you can just perform a calculation conversion to "correct" performance in clear gel so that it is relatable to ordnance gel.
Last edited by TGS; 04-14-2019 at 01:40 PM.
"Are you ready? Okay. Let's roll."- Last words of Todd Beamer
''Politics is for the present, but an equation is for eternity.'' ―Albert Einstein
Full disclosure per the Pistol-Forum CoC: I am the author of Quantitative Ammunition Selection.
As noted, put garbage in, you get garbage out....
Believe what you want, yet it is pretty simple (as reflected in my sig line below); if synthetic tissue simulant was so great, then major USG, DOD, LE, and medical research institutions would be using it--yet NONE do so, as the synthetics are NOT accurate or relevant to what is seen in real world GSW's.
Last edited by DocGKR; 04-14-2019 at 03:26 PM.
Facts matter...Feelings Can Lie
But would you use a round with repeatedly poor performance in clear gel when there are plenty of rounds that do well in both clear & organic gel? I'm thinking of rounds like that 147 Gold Dot (especially from a 3" barrel ccw into a potentially high BMI/lower density American criminal).
Personally, I'd rather have a robust expansion window...
Last edited by 0ddl0t; 04-14-2019 at 09:58 PM.
Yes. Partially because there's no established performance metrics for bullets in clear gel. You're making a conclusion that something does "poorly" in clear gel when there's no validated testing protocol for using clear gel.
lulz da fuq does that even mean. "Robust expansion window". There's no validation to clear gel. There's no validated parameters for what a bullet is supposed to do in clear gel in order to be correlated with successful street shootings. It's not correlated to anything. There isn't any window.
"Are you ready? Okay. Let's roll."- Last words of Todd Beamer
From everything I've seen, I agree. But given the practical advantages, why hasn't anyone tried to fix the synthetics? The i'm sure the important physical/chemical characteristics of organic ordinance gelatin cold be determined and measured. That being the case, CB, or someone else should be able to come up with a synthetic formulation that matches those, without having the functional negatives of organic ordinance gelatin. I would thing agencies/companies that use this stuff a lot would push for this. It would probably make their lives easier.
It is all a conspiracy by the gello and refrigerator makers...
That has been investigated to some extent, but there still remain to be resolved serious discrepancies relating to how PAGs respond to the passage of projectiles and how they represent temporary and permanent cavities. Even after matching the mass density of 10% ordnance gelatin (some elastomers do come close to at 0.90 - 1.10 grams/cm3), PAGs exhibit strain rate dependence (which has to do with how fast a projectile passes through the PAG), and energy storage and elastic moduli differences (these relate to the correct representation of the temporary cavity and also to the permanent cavity) that fall at the lower range of what is typically seen with 10% ordnance gelatin.
It is for these reasons that PAGs―especially poorly formulated PAGs like the CBG product―fail to represent certain high-velocity effects correctly. In addition to failing to produce forces comparable to those arising in 10% gelatin, CBG has a well-known tendency to produce less projectile expansion and correspondingly (rather unpredictable) greater penetration depths.
For your review, I have attached a PDF that, while a bit technical, might answer some of your questions.
Last edited by the Schwartz; 04-15-2019 at 04:12 PM.
''Politics is for the present, but an equation is for eternity.'' ―Albert Einstein
Full disclosure per the Pistol-Forum CoC: I am the author of Quantitative Ammunition Selection.