Predictive tests in water

[Glenn E. Meyer]

This will be informative for the:

1. Can I shoot my Glock underwater
2. What round for giant squid
3. What should Aquaman carry for EDC as a bug for his trident.

Sorry.

[the Schwartz]

This will be informative for the:

1. Can I shoot my Glock underwater
2. What round for giant squid
3. What should Aquaman carry for EDC as a bug for his trident.

Sorry.

No need to apologize.

I thought it was hilarious!

Especially the point about the giant squid.

[the Schwartz]

HCM,

I failed to address this part of your post and wanted to confirm that the correlative data pool also contains data points involving various barriers.

So you are comparing water to bare gel tests.

Here is one such example:

Firearm: 9mm Glock 19, 102mm barrel
Barrier: 2 layers of 8-ounce denim
Gelatin: nominal 10% concentration
Block Calibration : 3.20 ± 0.05 inches @ 585 ± 0.50 fps
Block Calibration Temperature : 37.70° ± 0.05 Fahrenheit
Block Core Temperature : 40.10° ± 0.05 Fahrenheit
Test Site Conditions: 68° Fahrenheit @ 46% relative humidity
Time out of refrigeration prior to shot impact: 7 minutes
Range: 10 feet



Average Expansion: 0.535 ± 0.0005 inch
Recovered Bullet Length: 0.526 ± 0.0005" inches
Recovered Bullet Weight: 147.5 ± 0.05 grains
Impact Velocity: 969 fps
Maximum Penetration Depth: 15.40 ± 0.05 inches
Maximum Cavitation Depth : 14.20 ± 0.05 inches

The comparison of the Q-model and mTHOR model's yields (specifically DoP) to the test above shows that these model's predictions are not affected by the presence of barriers.

Q-model
DoP: 15.986 inches
Wound Mass: 1.770 ounces
Wound Volume: 2.944 cubic inches

mTHOR
DoP: 15.198 inches
Wound Mass: 1.682 ounces
Wound Volume: 2.799 cubic inches

Probability of Incapacitation, 1st-shot and cumulative binomial P_[I/H] values
1st-shot P_[I/H]: 69.67%
2nd-shot P_[I/H]: 89.55%
3rd-shot P_[I/H]: 96.62%
ΔE₁₅: -189.871 fpe

DoP = maximum equivalent depth of penetration in calibrated 10% ordnance gelatin
Wound Mass = total weight of tissue damaged/destroyed within the entire wound channel
Wound Volume = volume of the entire wound channel
P_[I/H] = probability of incapacitation per random munition strike to combatant's torso/abdomen: Assault, 30-second time-frame (US Army BRL P_[I/H] model, Dziemian, 1960)
ΔE₁₅ = Amount of kinetic energy (in fpe) expended by the bullet from a penetration depth of 1 through 15 centimeters

[scjbash]

Technical aspects and comparisons to gel aside (I'm unqualified to speak on it), trying to put a number on the probability of incapacitation is ridiculous.

[Unobtanium]

If we compare gel to people, why not water to gel? Water and gel have a whole lot more in common with people.

Gel simulates homogeneous, uninterrupted muscle. What person have you met that you can get 12" of penetration through homogeneous, uninterrupted muscle on without using a Serpa holster?

[the Schwartz]

Technical aspects and comparisons to gel aside (I'm unqualified to speak on it), trying to put a number on the probability of incapacitation is ridiculous.

There are numerous research sources that suggest that such modelling, based upon ΔE₁₅ and P_[I/H] (re: Sturdivan, Dziemian, etc.) or a similar concept referred to as ''ballistic dose'' (re: Sperrazza & Kokinakis), is valid.

Hopefully, you'll find the following links that I've attached to be interesting/informative-

http://www.dtic.mil/dtic/tr/fulltext/u2/a240295.pdf

http://www.dtic.mil/dtic/tr/fulltext/u2/a526125.pdf

http://www.dtic.mil/dtic/tr/fulltext/u2/359774.pdf

http://www.dtic.mil/dtic/tr/fulltext/u2/a058947.pdf

http://www.dtic.mil/dtic/tr/fulltext/u2/365619.pdf

[PNWTO]

Probability of Incapacitation, 1st-shot and cumulative binomial P_[I/H] values
1st-shot P_[I/H]: 69.67%
2nd-shot P_[I/H]: 89.55%
3rd-shot P_[I/H]: 96.62%
ΔE₁₅: -189.871 fpe

@DocGKR, care to weigh in?

[the Schwartz]

@DocGKR, care to weigh in?

For the sake of clarity, it should be noted that the logistic equation for determining the probability of incapacitation, P_[I/H], being employed was developed Dziemian (1960), US Army Ballistic Research Laboratory at Aberdeen Proving Grounds;

P_[I/H] = [1 + e ^{-(-a + b(logΔE15))}]^-1

where-

a = 3.023
b = 1.651
e ≈ 2.718281828

-and the cumulative binomial distribution probability, ∑P_[I/H], equation for successive shots is-

∑P_[I/H] = 1 - (1 - P_[I/H])ⁿ ; P(X > x)

where 'n' is the number of trials, or in this case, successive number of rounds striking a combatant in the torso.

This approach, amongst others, for determining P_[I/H] can be found here:

http://www.dtic.mil/dtic/tr/fulltext/u2/a240295.pdf

[Wyoming Shooter]

This is fascinating stuff. Are commercial ammo producers using these models? Best, ELN.

There are numerous research sources that suggest that such modelling, based upon ΔE₁₅ and P_[I/H] (re: Sturdivan, Dziemian, etc.) or a similar concept referred to as ''ballistic dose'' (re: Sperrazza & Kokinakis), is valid.

Hopefully, you'll find the following links that I've attached to be interesting/informative-

http://www.dtic.mil/dtic/tr/fulltext/u2/a240295.pdf

http://www.dtic.mil/dtic/tr/fulltext/u2/a526125.pdf

http://www.dtic.mil/dtic/tr/fulltext/u2/359774.pdf

http://www.dtic.mil/dtic/tr/fulltext/u2/a058947.pdf

http://www.dtic.mil/dtic/tr/fulltext/u2/365619.pdf

[the Schwartz]

This is fascinating stuff. Are commercial ammo producers using these models? Best, ELN.

None that I am aware of at this time.

There are only two ways to determine ΔE₁₅.

The first method is to fire a projectile into 10% ordnance gelatin while recording its flight through the test medium using high frame-rate recording to determine the projectile's velocity at the penetration depths of 1 and 15 centimeters. Using those two velocity values, ΔE₁₅ (the rate of dissipation of KE from the penetration depth of 1 through 15 centimeters) can be computed for use in the logistic equation for determining the probability of incapacitation.

The second method is to model the projectile history through the Q-model to determine ΔE₁₅ (the rate of dissipation of KE from the penetration depth of 1 through 15 centimeters) for use in the logistic equation. Of course, this means firing an expanding bullet into water for the purpose of obtaining the necessary test data (expanded average diameter, retained mass, impact velocity) so that the Q-model can be used to compute ΔE₁₅. I should also note that Duncan MacPherson's bullet penetration model (it's also a Poncelet form) can also be used for this purpose with just a little algebraic rearrangement.

For most users, the complications and expense of using calibrated 10% ordnance gelatin are significant and being able to conduct such testing using water without the need of expensive high frame-rate recording equipment simplifies the process. Obviously, there are P-F members, like Tokarev, who do exceptionally good tests in gelatin, but the expense of a suitable high frame-rate camera (the $+100K Phantom comes to mind) is more than most are willing to bear.