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Thread: Ballistic gelatin comparisons: Part I

  1. #1

    Ballistic gelatin comparisons: Part I

    https://www.policeone.com/police-pro...dffb8-42778711

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  2. #2
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    Looking forward to reading the results.

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    Member Balisong's Avatar
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    WTF??? I read through all of that just to see no data provided in the "article"? I want to see where this goes, but the hell kind of journalism is that?

  4. #4
    Quote Originally Posted by Balisong View Post
    WTF??? I read through all of that just to see no data provided in the "article"? I want to see where this goes, but the hell kind of journalism is that?
    Of course there is no data, because it is not an honest journalistic piece. It's most likely nothing more than a marketing campaign being offered as journalism.

    The pressure that drives the expansion of bullets—like JHPs—is expressed by the Bernoulli pressure equation; P = ½ρV². As can be seen in the relatively simple Bernoulli pressure equation, pressure is dictated by two factors, those being the velocity, V, of the flow field relative to the projectile passing through it, and the mass density, ρ, of the test medium expressed in terms of mass per unit volume—usually as grams/centimeter³ or kilograms/meter³. For any specific projectile velocity, V, the pressure produced by identical projectiles having the same drag coefficient varies only according to the mass density of the test medium being traversed. If the mass density of a test medium (e.g.: 10% ordnance gelatin, water, etc.) differs significantly from that of soft tissue (that is, 1.020 — 1.060 grams/centimeter³) being physically modeled, then expansion and penetration depth data obtained in that medium will not correctly represent the expansion and penetration depth that occurs in actual soft tissue.

    Compared to the mass density of 10% concentration ordnance gelatin (which is ρ = 1.040 ± 0.020 grams/centimeter³), the mass density of Clear Ballistics Gelatin is 0.824 grams/centimeter³* which means that the pressure produced during all phases of the projectile's penetration through it will be on the order of 19.2% — 22.3% less than that occurring in either properly prepared 10% ordnance gelatin and/or human soft tissue analog (e.g.: usu. porcine thigh muscle tissue; 40 kg. pig). This means that projectile expansion will be less and that resultant penetration depth will be greater than that seen in 10% ordnance gelatin test medium.

    John Ervin, Mech. Eng. has a video here—

    https://www.youtube.com/watch?v=5pqP...ature=emb_logo

    —that compares the diminished expansion diameters and resulting increased penetration depth that occur in the clear, synthetic gelatin as opposed to 10% ordnance gelatin.

    At 18:45 in the linked video, Ervin provides a tabulated comparison of BB validation depths obtained in both 10% ordnance gelatin and the clear, synthetic gelatin test mediums.

    Name:  CBG v. 10% Gelatin shear response validation.JPG
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    The 10% ordnance gelatin passes the BB validation test confirming that it produces the correct shear response and will represent penetration depth correctly. The clear, synthetic gelatin does not pass the BB validation test and fails to produce the correct shear response meaning that it will not represent terminal penetration depth correctly.

    Ervin also has an entire webpage dedicated to comparing test data (expansion and penetration depth) obtained in both mediums here:

    http://www.brassfetcher.com/Syntheti...20Gelatin.html

    No single, simple, linear value for converting test results obtained in the clear, synthetic gelatin for comparison to those obtained in 10% ordnance gelatin is found to exist.

    If I've missed something, I am sure that Dr. Roberts can remedy any over-sight.

    *In the BrassFetcher webpage that compares test data obtained in both mediums, Ervin reports the mass density of the clear, synthetic gelatin as being 790 kilograms/meter³ which is equivalent to 0.790 grams/centimeter³ which is less than the quoted mass density of 0.824 grams/centimeter³ found in other literature as seen below.

    ETA: Additional documentation of test result discrepancies for expansion and penetration depths in the high-velocity regime in both test mediums can be found here: https://web.archive.org/web/20140216...Ballistics.pdf
    Last edited by the Schwartz; 11-13-2019 at 01:46 AM.
    ''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.

  5. #5
    Site Supporter 0ddl0t's Avatar
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    Quote Originally Posted by the Schwartz View Post
    Of course there is no data, because it is not an honest journalistic piece. It's most likely nothing more than a marketing campaign being offered as journalism.
    This was just part 1. I'm betting the data will be in part 3

    If the mass density of a test medium (e.g.: 10% ordnance gelatin, water, etc.) differs significantly from that of soft tissue (that is, 1.020 — 1.060 grams/centimeter³) being physically modeled, then expansion and penetration depth data obtained in that medium will not correctly represent the expansion and penetration depth that occurs in actual soft tissue.
    Granted, but a bullet might perform well in 10% ordinance gelatin yet fail to expand in fat (~ 0.9 g/cm^3). So while I understand the desire to compare penetration & expansion numbers across tests using identical media, I'd also like the bullet to have a robust design that allows it to reliably expand no matter how obese or muscular (~1.06 g/cm^3) the assailant is...

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    Member Balisong's Avatar
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    Schwartz, thank you for that awesome write-up!

  7. #7
    Quote Originally Posted by 0ddl0t View Post
    This was just part 1. I'm betting the data will be in part 3

    Granted, but a bullet might perform well in 10% ordinance gelatin yet fail to expand in fat (~ 0.9 g/cm^3). So while I understand the desire to compare penetration & expansion numbers across tests using identical media, I'd also like the bullet to have a robust design that allows it to reliably expand no matter how obese or muscular (~1.06 g/cm^3) the assailant is...
    According to this source: https://www.ncbi.nlm.nih.gov/pubmed/8148928

    —whole body (human) adipose tissue density ranges from 0.925-0.970 grams/centimeter³ and is more closely represented in terms of density related pressure effects by both 10% ordnance gelatin (ρ = 1.040 ± 0.020 grams/centimeter³) and water (ρ = 0.991625 ± 0.0041225 grams/centimeter³). Given the smaller difference between the mass density of whole body adipose tissue and these two test mediums (namely, 10% ordnance gelatin and water) it is hard to see any benefit offered by the use of the clear, synthetic gelatin which has a much lower mass density somewhere between 0.790 and 0.824 grams/centimeter³ over 10% ordnance gelatin or water.

    Averaged differences in mass density of test mediums and whole body adipose tissue:

    whole body adipose tissue: (0.950 ± 0.050 grams/centimeter³)

    Water, having a density of 0.991625 ± 0.0041225 grams/centimeter³, is 4.38% denser than adipose tissue with an average difference of 0.041625 grams/centimeter³
    10% ordnance gelatin: 1.040 ± 0.020 grams/centimeter³ is 9.47% denser than adipose tissue with an average difference of 0.090 grams/centimeter³
    clear, synthetic gelatin: 0.807 ± 0.017 grams/centimeter³ is 15.05% less dense than adipose tissue with an average difference of 0.143 grams/centimeter³

    Over the course of its use as a valid, repeatable terminal ballistic test medium, 10% ordnance gelatin has adequately represented the aggregate average density of the all of the tissues found in the human body, which ranges from very low density tissues like lung tissue (values obtained for the density of the upper, middle, and lower lung were 0.123 ± 0.46 g/cm³, 0.121 ± 0.033, and 0.154 ± 0.057 g/cm³ during inspiration and were 0.215 ± 0.058 g/cm³, 0.228 ± 0.066, and 0.260 ± 0.078 g/cm³ during expiration, respectively) [ https://www.ncbi.nlm.nih.gov/pubmed/2630782/] ] all the way to the mineral density of bone which ranges from 700 - 800 g/cm² in the human forearm to 1,000 - 1,200 g/cm² the human spinal column.

    Further, as Dr. Roberts has stated in a prior post here—

    Quote Originally Posted by DocGKR View Post
    A very close correlation between actual shootings and properly performed laboratory testing has been demonstrated for at least three decades now. In most properly conducted post-mortem evaluations, there is indeed a rough 1:1 ratio between gel and torso tissue––for example, Gene Wolberg's study of nearly 150 SDPD OIS incidents showed the majority of the 9mm 147 gr bullets fired by officers had penetrated about 13" and expanded between 0.60 to 0.62 inches in both human tissue and 10% ordnance gelatin. While there was a greater range of results in human tissue than in gel, the averages were nearly identical. Several other agencies with strong, scientifically based ammunition terminal performance testing programs have conducted similar reviews of their shooting incidents with much the same results––there is an extremely strong connection between properly conducted and interpreted 10% ordnance gelatin laboratory studies and the physiological effects of projectiles in actual shooting incidents. You just have to understand the anatomy and variables involved while making an evaluation. Note that projectiles from many real world shootings tend to behave like those in four layer denim testing.
    —I'd take this:

    "there is indeed a rough 1:1 ratio between gel and torso tissue"
    —as the final authoritative word on the suitability (in all respects) of 10% ordnance gelatin as a terminal ballistic test medium and its ability to represent the effects of the varying densities of the tissues found in the human body.
    Last edited by the Schwartz; 11-13-2019 at 01:52 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.

  8. #8
    Quote Originally Posted by Balisong View Post
    Schwartz, thank you for that awesome write-up!
    You are welcome.
    ''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.

  9. #9
    Site Supporter 0ddl0t's Avatar
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    Quote Originally Posted by the Schwartz View Post
    Over the course of its use as a valid, repeatable terminal ballistic test medium, 10% ordnance gelatin has adequately represented the aggregate average density of the all of the tissues found in the human body
    And in the aggregate, that's true. But near the boundaries of barrel length and bullet weight, testing solely in 10% OG has its flaws.

    Take 147 grain gold dots fired from a 3" barrel through heavy denim. They will perform fine in 10% ordnance gelatin, but completely fail to expand about half the time in clear gel. On the other hand, 147 grain HSTs perform well in both media. Which round would you load in your P365/PM9/Shield/LC9 (especially if you live in an area with an obesity epidemic)?

  10. #10
    Quote Originally Posted by 0ddl0t View Post
    And in the aggregate, that's true. But near the boundaries of barrel length and bullet weight, testing solely in 10% OG has its flaws.

    Take 147 grain gold dots fired from a 3" barrel through heavy denim. They will perform fine in 10% ordnance gelatin, but completely fail to expand about half the time in clear gel. On the other hand, 147 grain HSTs perform well in both media. Which round would you load in your P365/PM9/Shield/LC9 (especially if you live in an area with an obesity epidemic)?
    I would choose either of the designs based upon their performance in the 10% ordnance gelatin and/or in water. Both of these tissue analogs have long histories as valid terminal ballistic test mediums.

    The video above (provided here again)—

    https://www.youtube.com/watch?v=5pqP...ature=emb_logo

    —demonstrates without question that the clear, synthetic gel lacks the proper shear response which results in the under representation of projectile expansion and the over representation of penetration depth in ways that are neither predictable nor directly convertible (through the use of a constant conversion value) to values seen in the other proven mediums or in soft tissue including adipose tissue.

    Others have also found similar deficiencies in the performance of the clear, synthetic gel, too: https://www.youtube.com/watch?time_c...ature=emb_logo

    Why place blame on any bullet design for its performance in an inconsistent* test medium that has no proven/known representative equivalence to living tissue?

    The issue has been addressed adequately here—

    Quote Originally Posted by DocGKR View Post
    Also, despite much ill-informed You-Tube comments to the contrary, there is NO such thing as "FBI spec Clear Gel blocks"; to the best of my knowledge, NONE of the synthetic gel substitutes have ever been correlated with living tissue. In our experience and that of the FBI BRF, NONE of the synthetic gel substitutes have proven as accurate as properly conducted, validated 10% gel studies.
    —so I don't see the need to "re-invent the wheel".

    If anyone wants to waste their time and money testing ammunition in the clear, synthetic gel, that's their prerogative.









    *The manufacturer of the clear, synthetic gel routinely alters the formula of their product which is nothing more than a co-polymer plasticized by a paraffinic processing oil—which is Paralux 701 as last seen on a CBG purchase invoice that has circulated recently within industry channels.
    Last edited by the Schwartz; 11-14-2019 at 10:19 AM.
    ''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.

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