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Thread: Predictive tests in water

  1. #81
    Hornady .45 ACP 230 gr. XTP JHP +P (9096)

    Test Firearm: unmodified HK USP .45ACP with a 4.41'' barrel
    Barrier: 4 layers of 8-ounce cotton denim
    Range: 21 feet
    Test Medium: water @ 70° F

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    Average Diameter: 0.5947 inch
    Recovered Weight: 229.6 grains (99.83% retained weight)
    Impact Velocity: 922 fps
    Recovered Length: 0.495 inch

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    Predictive Analysis:

    Q-model
    DoP: 19.007 inches
    Wound Mass: 2.600 ounces
    Wound Volume: 4.325 cubic inches

    mTHOR
    DoP: 18.545 inches
    Wound Mass: 2.524 ounces
    Wound Volume: 4.199 cubic inches


    While the average predicted maximum penetration depth of this test ammunition is just a bit 'deep' at 18.776 inches (average predicted wound mass is 2.562 ounces), if this round were to exit a 12-inch deep human torso, its exit velocity would be on the order of 300 ― 325 fps which, due to being unstable after exiting a human body, is unlikely to produce a lethal injury in the event of an unintentional strike upon a down-range bystander.
    Last edited by the Schwartz; 11-18-2018 at 04:15 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.

  2. #82
    Site Supporter 0ddl0t's Avatar
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    Quote Originally Posted by the Schwartz View Post
    Diameter: 0.5787 inch
    Weight: 146.9 gr. (99.93% retained)
    Velocity: 1,006 fps

    ...

    Analysis:

    Q-model
    DoP: 13.710 inches
    Wound Mass: 1.776 ounces
    Wound Volume: 2.954 cubic inches

    mTHOR
    DoP: 13.300 inches
    Wound Mass: 1.723 ounces
    Wound Volume: 2.866 cubic inches
    Doesn't this methodology assume all projectiles have the same coefficient of drag? How do your formulae stand up to non standard projectiles like:

    tumbling fmj like 5.7 or Fort Scott
    unusual expansion shapes like Lehigh Extreme expansion
    fluted bullets like from underwood or polycase
    ?

  3. #83
    Quote Originally Posted by 0ddl0t View Post
    Doesn't this methodology assume all projectiles have the same coefficient of drag?
    No. Each projectile configuration in both the Q-model and mTHOR model has its own specific coefficient.

    Quote Originally Posted by 0ddl0t View Post
    How do your formulae stand up to non standard projectiles like:

    tumbling fmj like 5.7 or Fort Scott
    unusual expansion shapes like Lehigh Extreme expansion
    fluted bullets like from underwood or polycase?
    Within the limitations of closed-form equations like the modified Poncelet forms—proposed (respectively) by myself and MacPherson—and the mTHOR model; yes, they stand up quite well to the fluted and "non-standard" shapes. This thread is replete with examples of how well these relatively simple models (mine and MacPherson's) agree with and are confirmed by test data obtained in 10% ordnance gelatin.

    Against 891 data, an ANOVA for the Q-model has the following values:

    n = 891
    r = 0.940513
    r˛ = 0.884564
    95% confidence = ±0.345815 inch
    99% confidence = ±0.454477 inch
    T-test = 0.999962
    F-test = 0.700256

    ―and for the fitted mTHOR power law:

    n = 891
    r = 0.948401
    r˛ = 0.899465
    95% confidence = ±0.364299 inch
    99% confidence = ±0.478770 inch
    T-test = 0.875151
    F-test = 0.656238

    Coefficients do exist for projectile configurations having cruciform/fluted noses; many of them are proprietary.

    It is simply not possible to model projectiles that do not remain in a "nose-forward" attitude and "tumble" and/or reduce themselves to fragments using simple closed-form equations. Modeling "tumbling" projectiles and fragmentation (especially approaching complete disintegration) would require the use of numerical software (like LS-DYNA) modeling 10% ordnance gelatin as an isotropic, elastic-plastic material with linear strain-hardening and a cubic polynomial relationship (equation of state) between the hydrodynamic pressure and the gelatin's change in mass density. It is assumed that 10% gelatin would obey the von Mises yield criterion. Constitutive relations would need to supplement the polynomial EoS relating to internal sonic velocity, mass density and bulk modulus.
    Last edited by the Schwartz; 12-09-2019 at 01:11 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.

  4. #84
    Site Supporter 0ddl0t's Avatar
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    Is the measured penetration in water so meaningless it can be discarded? Are there often instances in which properly expanded projectile A travels farther in water than projectile B, yet where B travels farther in gel than A?
    Last edited by 0ddl0t; 12-09-2019 at 07:57 PM.

  5. #85
    Quote Originally Posted by 0ddl0t View Post
    Is the measured penetration in water so meaningless it can be discarded? Are there often instances in which properly expanded projectile A travels farther in water than projectile B, yet where B travels farther in gel than A?
    Yes (to your first question) and sometimes, but not usually (to your second question).

    While there are certainly simple "conversion factors" such as those suggested in Fackler ML. Simplified Bullet Effect Testing. Wound Ballistics Rev. 2001;5(2): 21-24, the practice of using over-simplified numerical conversion factors carries with it the risk of significant error. Dr. Fackler goes as far as to offer a cautionary comment to this approach (on page 21) in the cited article stating that, "Most bullets will penetrate about 1.5 times as far in water as in standard 10% ordnance gelatin: some penetrate even farther." I suspect that Dr. Fackler was fully aware of the potential short-comings of employing such a simplistic approach.

    Of course, such simple penetration equations like the modified Poncelet penetration equations in common use do not require these values, but bulk modulus (k), mass density (ρ), and internal speed of sound (c) as related to one another by the Newton-Laplace equation do have very much to do with the terminal ballistic behavior of projectiles in 10% ordnance gelatin—especially when using FEM software (LS-DYNA).
    Last edited by the Schwartz; 12-09-2019 at 08:34 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.

  6. #86
    Site Supporter 0ddl0t's Avatar
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    Thanks. I'm having a hard time wrapping my head around the precision of the estimation given so few input variables.

    I mean this:
    Quote Originally Posted by the Schwartz View Post
    the fitted mTHOR power law:

    n = 891
    95% confidence = ±0.364299 inch
    99% confidence = ±0.478770 inch
    suggests the following result is one of only ~9 gel tests that fell outside the 99% confidence interval for mTHOR...

    Quote Originally Posted by the Schwartz View Post
    Attachment 29424

    Average Expansion: 0.888 inch
    Recovered Slug Weight: 419.8 grains (97.45% retained weight)
    Impact Velocity: 1,256.6 fps
    Maximum Penetration Depth: 17.75 inches

    ...

    mTHOR
    DoP: 19.029 inches
    Last edited by 0ddl0t; 12-09-2019 at 09:55 PM.

  7. #87
    Quote Originally Posted by 0ddl0t View Post
    Thanks. I'm having a hard time wrapping my head around the precision of the estimation given so few input variables.
    Sometimes, I do, too.

    Both equations do extraordinarily well within their design limits.

    MacPherson's bullet penetration model also does quite well when compared against the same data set:

    n = 891
    r = 0.950263
    r˛ = 0.902999
    95% confidence = ±0.367783 inch
    99% confidence = ±0.483348 inch
    T-test = 0.922177
    F-test = 5.8x10-5
    ''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. #88
    Wanting a compact EDC option for this summer, one of my former partners, a retired Supervisory U.S. Customs Agent, recently purchased a brand new Ruger MAX-9 in 9mm Luger. We evaluated the performance of the Hornady 9mm 115-grain FTX® Critical Defense® JHP (#90250) projectile using water as a test medium.

    In the interest of clarity, two test protocols were conducted. The first test protocol was without an intermediate barrier to establish a minimum performance baseline. If the outcome produced by the first test protocol was successful then a second test protocol consisting of firing the test ammunition through the IWBA standard barrier consisting of 4 layers of 16-ounce denim (a simple mechanical failure test) would be conducted.

    Here are the results of those two tests:

    Walter, my son and ever-faithful lab assistant, handled the experimental set up and pulled the trigger on the first test protocol.

    Here he is holding the recovered projectile from that test—

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    Hornady 9x19mm 115 gr. FTX Critical Defense (#90250)

    Date: 15th June 2021
    Temperature: 75°F
    Relative Humidity: 42%

    Test Firearm: unmodified Ruger MAX-9, 9mm Luger
    Barrel Length: 3.20 inches
    Barrier: None
    Test Medium: H₂O @ 68°F
    Range: 21 feet

    Average Expanded Diameter: 0.5379 ± 0.0005 inch
    Recovered Weight: 114.1 grains
    Recovered Length: 0.387 inch
    Impact Velocity: 1,007 fps

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    Predictive Analysis:

    Q-model
    DoP: 12.53 inches
    Permanent Wound Mass: 1.40 ounces
    Wound Cavity Volume: 2.33 cubic inches


    mTHOR algorithm
    DoP: 11.97 inches
    Permanent Wound Mass: 1.34 ounces
    Wound Cavity Volume: 2.23 cubic inches


    For the sake of comparison, the McPherson WTI bullet penetration model was also used to predict maximum terminal penetration depth and total permanent wound mass. The predictive yield from the McPherson WTI bullet penetration model was a DoP of 12.38’’ having a total permanent wound mass of 1.16 oz.

    The Hornady 9mm 115-grain FTX® Critical Defense® JHP successfully passed this test protocol.

    The Hornady 9mm 115-grain FTX® Critical Defense® JHP was then evaluated against the second test protocol.

    =========================================

    Hornady 9x19mm 115 gr. FTX Critical Defense (#90250)

    Date: 15th June 2021
    Temperature: 75°F
    Relative Humidity: 42%

    Test Firearm: unmodified Ruger MAX-9, 9mm Luger
    Barrel Length: 3.20 inches
    Barrier: IWBA 4 layers of 16-ounce cotton denim
    Test Medium: H₂O @ 68°F
    Range: 21 feet

    Average Expanded Diameter: 0.5216 ± 0.0005 inch (asymmetric)
    Recovered Weight: 114.2 grains
    Recovered Length: 0.649 inch
    Impact Velocity: 1,005 fps

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    Name:  2.) Hornady 9mm Critical Defense, 115-grain FTX (4LD) Ruger MAX-9 3.2'' barrel @ 1,005 fps (4LD).jpg
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    Predictive Analysis:

    Q-model
    DoP: 13.411 inches
    Permanent Wound Mass: 1.411 ounces
    Wound Cavity Volume: 2.347 cubic inches


    mTHOR algorithm
    DoP: 12.718 inches
    Permanent Wound Mass: 1.338 ounces
    Wound Cavity Volume: 2.226 cubic inches


    Because the Hornady 9mm 115-grain FTX® Critical Defense® JHP failed to produce reliable, uniform expansion after passing through the IWBA standard barrier consisting of 4 layers of 16-ounce denim, my former partner rejected it as an option and decided to continue testing other candidate ammunition for his new EDC.
    Attached Images Attached Images  
    Last edited by the Schwartz; 07-11-2021 at 02:30 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.

  9. #89

    Norma 9x19mm 108-grain MHP (299740020) in the Ruger MAX-9

    While we had the test materials and set up available, we also ran the Norma 9x19mm 108-grain MHP (299740020) through the Ruger MAX-9 just to see how it would behave from a shorter-than-service-length (< 4'') barrel after passing through the IWBA standard barrier consisting of 4 layers of 16-ounce denim. Not surprisingly, there seems to be a lower velocity limit at which the Norma MHP will not expand.

    Norma 9x19mm 108-grain MHP (299740020)

    Date: 15th June 2021
    Temperature: 75°F
    Relative Humidity: 42%

    Test Firearm: unmodified Ruger MAX-9, 9x19mm
    Barrel Length: 3.20 inches
    Barrier: 4 layers of 16-ounce cotton denim
    Range: 21 feet
    Test Medium: H₂O @ 68°F

    Average Expanded Diameter: 0.355 ± 0.0005 inch
    Recovered Weight: 108.4 grains
    Recovered Length: 0.655 inch
    Impact Velocity: 1,049 fps

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    Predictive Analysis:

    Q-model
    DoP: 23.437 inches
    Wound Mass: 0.960 ounces
    Wound Cavity Volume: 1.597 cubic inches

    mTHOR model
    DoP: 23.320 inches
    Wound Mass: 0.955 ounces
    Wound Cavity Volume: 1.589 cubic inches


    Testing of the Norma 9x19mm 108-grain MHP from the 3.20-inch barrel of the Ruger MAX-9 was halted after it failed to fully expand in the water test medium after passing through 4 layers of 16-ounce cotton denim. The nose of the bullet was only slightly deformed with two of the four skived expansion cavity wall sections pushed inward about 1.5 millimeters at impact displacing the other two skived expansion cavity wall sections outward about 1.5 millimeters. Predicted penetration depth, permanent wound mass, and wound cavity volumes of the test projectile were modeled as for an FMJRN while assuming that it would maintain nose-forward stable flight through the test medium.
    ''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.

  10. #90
    A few months ago, I purchased a box of Norma's latest offering, the Norma 9mm 108-grain Monolithic Hollow Point (MHP).

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    Not only was I curious as to how fast Norma's new design would leave the 4.49-inch barrel of my EDC, an otherwise stock Glock 17 with Heinie target sights, I also wanted to see how it would perform after passing through the IWBA standard failure test of four layers of 16-ounce denim.

    The velocity from my Glock 17's barrel is about 85 - 130 fps slower than Norma's advertised velocity of 1,312 fps but, in all fairness, Norma's advertised velocity is obtained from a 6-inch test barrel according to the information printed on the side of their product's box. With that thought in mind, the lower velocities that I obtained from my Glock 17's 1.5-inch shorter barrel appear to be what anyone could reasonably expect.

    Here is the 1st IWBA 4LD test—

    Norma 9x19mm 108-grain MHP (299740020)

    Date: 15th June 2021
    Temperature: 75°F
    Relative Humidity: 42%

    Test Firearm: unmodified Glock 17, 9x19mm
    Barrel Length: 4.49 inches
    Barrier: 4 layers of 16-ounce cotton denim
    Range: 21 feet
    Test Medium: H2O @ 68°F

    Average Expanded Diameter: 0.6504 ± 0.0005 inch
    Recovered Weight: 108.4 grains
    Recovered Length: 0.393 inch
    Impact Velocity: 1,183 fps

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    Predictive Analysis:

    Q-model
    DoP: 8.67 inches
    Wound Mass: 1.42 ounces
    Wound Cavity Volume: 2.36 cubic inches


    mTHOR model
    DoP: 8.76 inches
    Wound Mass: 1.43 ounces
    Wound Cavity Volume: 2.38 cubic inches

    Simply for the sake of comparison, this water test data was also evaluated using the McPherson WTI model with the following results of DoP of 9.54 inches and a Wound Mass of 1.24 oz.

    DoP = depth of penetration in inches
    ''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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