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The Next “Step” for Reloading?

by Charles Schwartz

August 27th, 2019

     One of the things that has always impressed me most about those who reload or manufacture their own ammunition is the nearly universal tendency to minimize those variables that effect the accuracy of their final product. I’ve observed that as a group, those who handcraft their own ammunition from used (or even brand new) components exhibit tremendous attention to detail and control over everything ranging from average cartridge weight, neck-wall thickness, case neck length, primer pocket uniformity and average case volume to case manufacturer, propellant type, and overall cartridge length. Then, there is the practice of case preparation that includes all sorts of labor-intense machinations such as primer pocket reaming, case-resizing and cleaning, case neck turning and trimming and many other operations that make my head hurt just trying to keep track of them all. Once assembled, the final product is subjected to all sorts of “quality-control” operations in the form of measuring for round-to-round conformity and projectile concentricity, then checking cartridge performance over a chronograph for speed and consistency, and finally, inspecting the fired cases for signs of excessive pressure. Indeed, those who participate in this hobby—some rightly call it a “passion”—are a meticulous lot to be sure. If this hobby was a “vacation”, all of the “fun” to be had would be in “getting there” although I am told, there is some satisfaction to be found in the final refined product. However, there remains one last “step” in this procedural paradise called reloading. That “step” is water-testing the painstakingly assembled ammunition to confirm that it delivers the desired terminal performance. More on that later…

Recently, I’ve begun to notice a marked increase in interest among my fellow shooting enthusiasts in loading and carrying light-weight jacketed hollow points at very high velocities—1,400 fps to 1,600 fps or more—for the purpose of self-defense. Obviously, velocity is necessary for a JHP to do what it is supposed to do. Otherwise, we have nothing more than an inert chunk of lead or copper laying on the ground. However, two questions arising from this expressed preference now beg to be answered:

“At what point does increasing velocity become ‘too much’?”

“At what point does decreasing projectile mass become ‘too light’?”

Armed with these questions, and a desire to uncover the facts for myself, I headed to the range with a few dozen water-filled ½-gallon paperboard beverage cartons to find out for myself. In Chapter 6 of Quantitative Ammunition Selection, I describe an alternative water-testing method that lends itself to uncommon convenience. Since that alternative method re-uses empty paperboard cartons that are eventually destined for the recycling center anyway, it is also a “green” practice that is likely to make even the staunchest environmentalist smile…even if only a little bit. As can be seen in the following image, set-up is a fairly straight-forward proposition. For the sake of stability and alignment, it helps to have a level, sturdy surface to line-up the ½-gallon paperboard cartons. In this case, it’s my preferred option; an old picnic table re-tasked for water-testing ammunition. I recommend using at least 12 cartons. This number of cartons ensures that even if the test bullet penetrates a little further than anticipated, that it will still be captured for evaluation using the mathematical bullet penetration models described in this article.

As can be seen in the image, care must be taken to align not only the ½-gallon paperboard cartons in a straight line, but also to make sure that the chronograph is properly positioned in front of the cartons for pre-impact velocity measurement of the test projectile. Protecting the electronic “guts” of the chronograph from water that invariably splashes back from the cartons at impact can be accomplished with a few layers of cheap paper shop towels placed over the chronograph so that they do not obstruct the detection ports of the chronograph. Once everything is in place, it’s all fun from here on out.

Before getting to the test results, I would be remiss if I failed to mention the one other significant benefit of water-testing ammunition. Besides being an inexpensive yet scientifically-valid and reliable methodology that allows us to predict the terminal ballistic performance of our ammunition, it offers one other significant benefit. Of the only two valid terminal ballistic test mediums extant (10% concentration ordnance gelatin and water), testing in water is known for its ability to produce expansion in the toughest/resistant JHP designs and serves as a valuable discriminator for designs that simply will not perform under even the best conditions. In other words, if a JHP bullet will not expand in water, it probably won’t expand in human or animal soft tissue either.

As for the ammunition that I tested, I selected three different light-weight, high-velocity 9mm JHPs from three different manufacturers for the two test regimens that I intended to subject all of them to. The ammunition that I chose for this test series was the Corbon 9mm 90-grain JHP, the SuperVel 9mm 90-grain (Nosler) JHP, and the DoubleTap 9mm 80-grain Barnes TAC-XP HP. The first test regimen is a control test (no barrier) designed to ensure that the test bullets were able to expand as designed. In this case, test bullets would be fired over the chronograph and directly into the water test medium without having to pass through a barrier of any sort. This test regimen served as the base line for further comparison of the three selections. The second test regimen consists of firing the selected loads over the chronograph and through the IWBA (International Wound Ballistics Association) standard barrier of four layers of 16-ounce denim. While I’ve seen the IWBA 4LD test method criticized far and wide as being unrealistic with declarations of (accompanied by lots of eye-rolling), “No one walks around wearing four layers of heavy-weight denim clothing!”, simulating street clothing is not the purpose of the IWBA 4LD test. The IWBA four layer denim (4LD) test is simply a mechanical failure test that is intended to represent a “worst case” mechanical barrier that challenges the expansion performance (and its resistance to plugging up) of the JHP being tested. In my experience, these two tests provide a convenient yet sufficient basis for establishing a JHP design as being suitable for use in most conceivable and frequently encountered self-defense situations.

After testing was completed and the test projectiles were recovered from the ½-gallon cartons, their terminal ballistic performance was assessed using the two mathematical bullet penetration models found in Quantitative Ammunition Selection. The first bullet penetration model, which I often refer to as the Q-model, used to assess terminal performance is found in Chapter 3. The Q-model is a modified Poncelet penetration equation in which the empirical variable, called “characteristic velocity” (denoted by Poncelet symbolically as co) has been (re)defined mathematically in terms of specific target material physical properties. Other iterations of the commonly modified Poncelet form do exist, but none matches the Q-model in terms of predictive accuracy when compared against the nearly 900 independent 10% ordnance gelatin test data that has been amassed for the purpose of correlative/comparative analysis. The second bullet penetration model used to assess terminal ballistic performance is the mTHOR bullet penetration model found in Chapter 9 of Quantitative Ammunition Selection. The mTHOR bullet penetration model is derived from a 1950s-era armor penetration algorithm (Project THOR, April 1963) that was modified extensively for use in modeling the terminal ballistic performance of projectiles in human soft tissue.

The Water Test Results

The weather conditions on the day of these tests, Wednesday, July 10th 2019, consisted of mostly cloudy skies with a temperature of 89° Fahrenheit at 49% Relative Humidity. Distance to the target barrier face and water test medium was 10 feet. Each set of test results is presented with the “Control” test (no barrier) first followed by the IWBA 4LD mechanical failure test protocol.

 

1.) Corbon 9mm 90-grain JHP (control)

Test Firearm: Glock 17; 4.49-inch barrel

Barrier: None

Test Medium: H2O

 

Average Recovered Diameter: 0.524 inch

Retained Mass: 42.6 grains

Impact Velocity: 1,455 feet per second

Predictive Analysis:

 

Q-model

DoP: 6.162 inches

Wound Mass: 0.654 ounces

Wound Volume: 1.089 cubic inches

 

mTHOR model

DoP: 6.181 inches

Wound Mass: 0.656 ounces

Wound Volume: 1.092 cubic inches

 

Probability of Incapacitation

1st-shot P[I/H] : 64.60 %

2nd-shot P[I/H] : 87.47 %

3rd-shot P[I/H] : 95.56 %

ΔE15 : -156.822 fpe

 

 

 

2.) Corbon 9mm 90-grain JHP vs. 4 layers of 16-ounce denim

Test Firearm: Glock 17; 4.49-inch barrel

Barrier: IWBA 4LD mechanical failure test protocol

Test Medium: H2O

 

Average Recovered Diameter: 0.4895 inch

Retained Mass: 44.3 grains

Impact Velocity: 1,448 feet per second

 

Predictive Analysis:

Q-model

DoP: 7.414 inches

Wound Mass: 0.687 ounces

Wound Volume: 1.143 cubic inches

 

mTHOR model

DoP: 7.340 inches

Wound Mass: 0.680 ounces

Wound Volume: 1.131 cubic inches

 

Probability of Incapacitation

1st-shot P[I/H] : 65.21 %

2nd-shot P[I/H] : 87.90 %

3rd-shot P[I/H] : 95.79 %

ΔE15 : -162.814 fpe

 

3.) SuperVel 9mm 90-grain JHP (control)

Test Firearm: Glock 17; 4.49-inch barrel

Barrier: None

Test Medium: H2O

 

Average Recovered Diameter: 0.515 inch

Retained Mass: 47.5 grains

Impact Velocity: 1,524 feet per second

 

Predictive Analysis:

 

Q-model

DoP: 7.312 inches

Wound Mass: 0.750 ounces

Wound Volume: 1.248 cubic inches

 

mTHOR model

DoP: 7.384 inches

Wound Mass: 0.757 ounces

Wound Volume: 1.260 cubic inches

 

Probability of Incapacitation

1st-shot P[I/H] : 67.93 %

2nd-shot P[I/H] : 89.71 %

3rd-shot P[I/H] : 96.70 %

ΔE15 : -192.982 fpe

 

4.) SuperVel 9mm 90-grain JHP vs. 4 layers of 16-ounce denim

Test Firearm: Glock 17; 4.49-inch barrel

Barrier: IWBA 4LD mechanical failure test protocol

Test Medium: H2O

Average Recovered Diameter: 0.518 inch

Retained Mass: 49.4 grains

Impact Velocity: 1,520 feet per second

 

Predictive Analysis:

 

Q-model

DoP: 7.499 inches

Wound Mass: 0.778 ounces

Wound Volume: 1.295 cubic inches

 

mTHOR model

DoP: 7.576 inches

Wound Mass: 0.786 ounces

Wound Volume: 1.308 cubic inches

 

Probability of Incapacitation

1st-shot P[I/H] : 68.46 %

2nd-shot P[I/H] : 90.05 %

3rd-shot P[I/H] : 96.86 %

ΔE15 : -199.762 fpe

 

 

5.) DoubleTap 9mm 80-grain TAC-XP (control)

Test Firearm: Glock 17; 4.49-inch barrel

Barrier: None

Test Medium: H2O

Average Recovered Diameter: 0.574 inch

Retained Mass: 80.0 grains

Impact Velocity: 1,451 feet per second

 

Predictive Analysis:

 

Q-model

DoP: 9.472 inches

Wound Mass: 1.207 ounces

Wound Volume: 2.008 cubic inches

 

mTHOR model

DoP: 9.654 inches

Wound Mass: 1.230 ounces

Wound Volume: 2.046 cubic inches

 

Probability of Incapacitation

1st-shot P[I/H] : 73.94 %

2nd-shot P[I/H] : 93.21 %

3rd-shot P[I/H] : 98.23 %

ΔE15 : -290.110 fpe

 

 

6.) DoubleTap 9mm 80-grain TAC-XP vs. 4 layers of 16-ounce denim

Test Firearm: Glock 17; 4.49-inch barrel

Barrier: IWBA 4LD mechanical failure test protocol

Test Medium: H2O

Average Recovered Diameter: 0.560 inch

Retained Mass: 80.0 grains

Impact Velocity: 1,471 feet per second

 

Predictive Analysis:

 

Q-model

DoP: 10.071 inches

Wound Mass: 1.221 ounces

Wound Volume: 2.032 cubic inches

 

mTHOR model

DoP: 10.246 inches

Wound Mass: 1.243 ounces

Wound Volume: 2.067 cubic inches

 

Probability of Incapacitation

1st-shot P[I/H] : 74.16 %

2nd-shot P[I/H] : 93.34 %

3rd-shot P[I/H] : 98.28 %

ΔE15 : -295.386 fpe

 

DoP = maximum equivalent depth of penetration in 10% ordnance gelatin (or soft tissue)

Wound Volume = total volume of the permanent channel

Wound Mass = total weight of tissue damaged/destroyed within the permanent wound channel

P[I/H] = probability of incapacitation per hit: (Assault: 30 seconds)

ΔE15 = Amount of kinetic energy (in fpe) expended by the bullet from a penetration depth of 1 through 15 centimeters

The Analysis

Although I have covered it in prior articles, a quick review of the terminology used above to evaluate the terminal ballistic performance of the ammunition that was tested is in order. In 1961, the Bio-Physics Division of the US Army Ballistic Research Laboratory at Aberdeen Proving Grounds (BRL) produced a mathematically-based predictive personnel incapacitation equation based upon 7,898 wound data accumulated by the Wound Data Munitions Effectiveness Team (WDMET) during the Vietnam War. The equation was correlated to the WDMET wound data base by assigning the wound data to 16 functional groups (which specify discrete levels of functional disability) that comprise four representative tactical roles (assault, defense, supply, and reserve) across six post-wounding time frames (30 seconds, 5 minutes, 30 minutes, 12 hours, 24 hours and 5 days). The 16 functional groups, six time frames and four representative tactical roles are used to quantify the expected loss or decrease in combat effectiveness (that is, incapacitation) of an enemy combatant according to the wound classification and severity.

The US Army personnel incapacitation equation relies upon an incremental kinetic energy expenditure parameter (ΔE15) of a random munition strike to the center of mass (COM) of a combatant’s or assailant’s body over a penetration depth of 1 – 15 centimeters to predict a projectile’s probability of incapacitation, represented symbolically as P[I/H]. Greater values of ΔE15 equate to greater strain energy storage within surrounding tissues produced by the bullet’s passage through them. Increased strain energy storage increases the likelihood of proximate tissue damage and with that damage, an increased probability of incapacitation. The US Army personnel incapacitation equation takes the form of,

P[I/H] = [1 + e -(-a + b(logΔE15))]-1 ,

with the logistic equation’s fitted coefficients, ‘a’ and ‘b’ being dependent upon the tactical situation with respect to the two representative tactical roles of most interest where self-defensive scenarios are being assessed. These coefficients can be found in Chapter 10 of Quantitative Ammunition Selection. Fortunately, the dimensionally-based mathematical terminal ballistic model found in Chapter 3 of Quantitative Ammunition Selection allows mere mortals like you and me (who lack access to a taxpayer-funded and equipped laboratory) to use water testing to determine the ΔE15 parameter of our self-defense ammunition. Once ΔE15 has been determined, we can use that parameter to predict the P[I/H] of the self-defense ammunition being tested and evaluated. Since we are most interested in assessing the immediate ability of an assailant to perform the dynamic actions required to inflict grievous or lethal injury upon us during an armed confrontation, the most appropriate time frame and representative tactical role for assessing an assailant’s response capability is “Assault: 30 seconds”.

 

In reviewing the test results above, were I to choose a “winner”, it would have to be the DoubleTap 9mm 80-grain Barnes TAC-XP HP. Subjected to identical tests as the other two JHPs, the DoubleTap 9mm 80-grain Barnes TAC-XP HP exceeded the other two JHPs’ performance by significant margins in all of the important terminal ballistic performance measures.

 

A bullet must produce enough penetration to reach critical anatomy to incapacitate a lethal aggressor. Although none of the JHPs tested reached the preferred minimum penetration depth of 12 inches as recommended by the F.B.I. test protocols, the DoubleTap 9mm 80-grain Barnes TAC-XP HP exceeded the penetration depth of next best JHP, the SuperVel 90-grain Nosler JHP, by slightly more than 2.5 inches. That is 34% more penetration depth than the next best (SuperVel) JHP. Part of the performance picture is retained projectile mass. The DoubleTap 9mm 80-grain TAC-XP retained 100% of its initial mass in both tests.

 

Even though the other two JHPs were as fast as, or slightly faster than, the DoubleTap TAC-XP, it was not enough to compensate for the difficulty that the Corbon and SuperVel JHPs had losing about 50% of their pre-impact masses. This loss of mass through radical fragmentation by the Corbon and SuperVel JHPs, despite their respective velocities, directly affected penetration depth. Finally, the DoubleTap 9mm 80-grain TAC-XP HP produced the highest average probability of incapacitation (Assault: 30 seconds) across both tests at 74.05%. The average probability of incapacitation for the SuperVel 9mm 90-grain JHP was 68.20% and 64.91% for the Corbon 9mm 90-grain JHP. So, what if a JHP that is “custom-tailored” to produce the minimum 12 inches of penetration depth recommended by the F.B.I. test protocols is desired?

The Solution: Reloading!

Well, that’s where reloading and a friend of mine, Kevin Newberry, who has probably forgotten more about reloading than I and most people will ever know comes in handy. In a prior article that appeared on May 14th 2018 on the Western Powders Blog, Kevin produced a 9mm hand load that I believe is very likely the answer to that question.

One of the most important aspects of load development is the sectional density of the JHP being used. As a bullet’s sectional density is redefined during the process of expansion, it always decreases, so starting with the highest practical sectional density JHP is always desirable. For the .45 ACP, maximum practical sectional density is found with projectiles weighing 230 grains, for the .40 S&W it is for those weighing 180 grains and for the 9mm, it is 147 grains. Velocity is also a necessary component and pushing a bullet as fast as it can go (not exceeding the bullet’s designed “velocity range”) is also desirable so long as it does not render the load unmanageable in the end-user’s hands. In this case, the following hand load does all that could be asked of it—

Hornady 9mm 147-grain XTP JHP (7.4 grains of Accurate #7)

Test Firearm: Canik TP9sa; 4.47-inch barrel

Barrier: None

Test Medium: H2O

Average Recovered Diameter: 0.6035 inch

Retained Mass: 131.5 grains

Impact Velocity: 1,154 feet per second

 

Predictive Analysis:

 

Q-model

DoP: 12.210 inches

Wound Mass: 1.720 ounces

Wound Volume: 2.861 cubic inches

 

mTHOR model

DoP: 12.118 inches

Wound Mass: 1.707 ounces

Wound Volume: 2.839 cubic inches

 

Probability of Incapacitation

1st-shot P[I/H] : 73.30 %

2nd-shot P[I/H] : 92.87 %

3rd-shot P[I/H] : 98.10 %

ΔE15 : -277.192 fpe

 

With a retained mass of 131.5 grains, the Hornady 9mm 147-grain XTP JHP has enough momentum to reach of maximum penetration depth of 12.21 inches even with its post-expansion sectional density of 0.0516 down from its pre-impact sectional density of 0.1666. The expansion ratio of the 147-grain XTP JHP is perfection itself at approximately 1.7 times the initial diameter of the bullet which is slightly more than the 1.5 expansion ratio usually seen with XTPs. Undoubtedly, the superior velocity of 1,154 fps is the cause of the increased expansion ratio.

With the vast array of reloading components available these days, there are innumerable combinations of projectiles and propellants that, with a little effort (in the hands of a skilled reloader), can be used to extract the desired performance from the calibers that we carry to protect our loved ones. Bullet mass and expansion behavior can be changed by simply using another JHP projectile. Velocity can be altered by increasing or decreasing the amount of propellant or selecting an entirely new propellant altogether. And if this wasn’t enough, being able to test the products of those efforts through water testing is just another “step” in the reloading process and an incredibly fascinating one at that!

Quantitative Ammunition Selection is available domestically and internationally in hardcover, paperback, and eBook formats and may be purchased at www.quantitativeammunitionselection.com