Statistical Analysis of "Energy Transfer"

[RyanM]

If you want to fiddle with the numbers and graphs yourself, attached is the spreadsheet with just the figures, and no graphs. Bullet descriptions are extremely vague, since it was already exhausting enough to type out all those darn numbers. If you want to try correlating them to the actual shots, data was put in in about the same order as the sources are listed.

And I really would say that correlation is close to nil, when you look at the results for plotting just rounds of a single caliber. If increasing energy really does increase wounding ability, shouldn't putting more energy on a 9x19mm (or other) bullet increase the performance? Shouldn't .357 magnum results consistently be above and to the right of 9mm parabellum? Plotting hasn't shown much of a difference, though.

Sure, more energy = more damage when comparing a .38 and a .44, but that type of comparison is pretty much the main reason for the total graph showing any correlation.

 

[Shane333]

I'm very interested in this. Right now I'm using a CZ83 (.380) with Rem. GoldenSaber 102 gr. bullets. I'd hoped the heavier .380 HP bullet would give me best balance of weight and expansion. However, if penetration is the single most important variable, I may do much better finding a hot loaded FMJ cartridge.

I'd love to see the data sorted by caliber.

 

[RyanM]

The majority of my .380 ACP data was from http://www.stevespages.com/page8f380acp.html

Since those shots were fired into water jugs, divide penetration depth by 1.5 for approximate penetration in gelatin. The IWBA's minimum penetration is 12.5" in gelatin (~19" in water), and the FBI's minimum is 12" (18" water). On there, Golden Saber only managed the equivalent of 9.33".

Penetration is really only the most important variable when comparing cartridges and guns that you already shoot well. Shot placement is probably the single most important factor, but inadequate penetration can negate shot placement.

The biggest single example I can think of, and the reason for the FBI's penetration requirement, is the 1986 Miami shootout. Early on in the gunfight (the first gunshot wound which Platt received, in fact), Special Agent Dove hit Platt in the right arm, just above the elbow, with a 9mm +P 115 grain Winchester Silvertip. The bullet severed Platt's brachial artery, cutting off all blood flow to Platt's right hand, and kept going into his chest, severing several large blood vessels in there; at autopsy, Platt's right lung was totally collapsed and nearly a quart and a half of blood was in his chest cavity. That bullet stopped one inch short of penetrating his heart.

Despite the severity of the wound (in fact, it was that wound which actually killed Platt; while Mireles was able to stop both Platt and Matix with spinal cord hits, Platt actually bled to death due to the bleeding from Dove's first hit), and the fact that his right arm was hit again by a shot which shattered his radius (forearm bone on the thumb side), almost totally disabling his right hand, Platt was able to shoot Special Agent McNeill in the neck, SA Grogan fatally in the chest, SA Dove twice in the head, and SA Hanlon in the groin.

If the bullets issued to those FBI agents had penetrated 2 or 3 inches more, Dove's shot would have struck Platt in the heart, and it's estimated that he would have bled out much sooner; a matter of inches could have saved two lives, a neck, and a groin. 9mm 115 grain +P Silvertips penetrate only around 9" in gelatin, thus the current FBI requirement is 12" to 18".

 

[JohnKSa]

If increasing energy really does increase wounding ability, shouldn't putting more energy on a 9x19mm (or other) bullet increase the performance?

The numbers aren't designed to test that premise. There are many more variables than just bullet energy in those numbers.

One thing I keep saying that so far has been completely ignored is that wound channel size depends heavily on penetration and penetration is tightly controlled by ammo makers--at least in their premium SD loadings. That throws a big monkey wrench into the results here--you have ammunition designers intentionally limiting penetration and therefore wound channel size. Plotting these plots as if energy is the main variable totally ignores that fact.

That's what I was saying with my earlier post. You can see a clear linear trend up to about 300ft/lbs. My speculation is that 300ft/lbs is the point at which an ammo manufacturer can guarantee good expansion with "ideal" penetration. BEFORE that point, they're getting good expansion, but they can't get "ideal" penetration. So the wound channels are getting deeper and deeper as the energy goes up. At the 300ft/lb mark the linear trend goes away because everything's making ideal (or can easily be made to make ideal) penetration so then wound channel size starts to become more dependent on the ability of the ammo designer.

 

[MrAcheson]

I did a little work and sorted through the numbers by caliber.

The navy blue rounds are the mouseguns.

The yellow rounds are the low pressure .38/9mm calibers like the blowbacks and .38special.

The reds are the higher pressure 9mm rounds.

The lighter blue rounds are .40 and 10mm.

The greens are the .44specials and .45s.

The 2 blacks are .44mag and .30 carbine.

I'll do more work with this when I get a little free time.

 

[MrAcheson]

I looked at it a little more. The reason that 9mm is doing poorly is basically that there is an expansion ceiling it can't pass. The 9mm/.38s average around ~.55 inches. The .44/.45s average a much higher .71 inches. The penetration is similar (12 vs. 13) but the .45s frontal area is almost twice as much (.24 sq in vs. .40 sq in).

So we come back to whether this wound model is accurate or not.

 

[coylh]

Can I take a moment, and compliment all involved in this thread: it's better than 90% of the gun magazine articles I've read! This is facinating stuff!

 

[RyanM]

The reason that 9mm is doing poorly is basically that there is an expansion ceiling it can't pass.

Sounds about right to me. .355" to .55" is 1.55x expansion, while .451" to .71" 1.57x expansion. Bigger bullet = bigger hole, since I believe bullet size makes more of a difference than velocity. Not 100% certain, though.

Though if you want to, it's no huge task to graph for anything else you want. Let's see, surface area of a cylinder, and surface area of a cone...

Surface area of cylinder:

Surface area of cone:

And then because higher velocity bullets usually make a bigger hole for a given expanded diameter, volume of a cylinder * velocity:

Interesting, a much stronger correlation. Of course, the same variable (velocity) being used on both axes might be to blame. Still, let's see if the correlation holds up when seperating by calibers...

All 9mm (.355" to .364") calibers:

Correlation seems to be holding up.

But then when plotting 9x19mm alone:

Oops, falls apart again. Plotting any individual caliber like that results in even more chaotic results.

I'll leave it to the reader to determine if using the same variable on both axes is valid or not.

 

[RyanM]

.40 and 10mm graphed together produce pretty poopy results:

And graphing .44 and .45 (all) together isn't much better:

 

[coylh]

Ryan: I feel your pain. I searched for every 9mm Gold dot gelatin shooting I could get my hands on. I picked that one because it's my carry load. Then tried to figure out Excel's formulas. Please correct if I did anything wrong.

I wanted to see what happens when the same bullet (as much as possible) is charted at different energy levels. I've included the spreadsheet in case anyone wants to see the data.

 

[RyanM]

Looks like better correlation on Gold Dots. But were the results all three weights (or more, if they make them), or predominantly 1 or 2? I spot a couple "fliers" above the main line, which I'd bet are 147 grain ones.

In the case of Gold Dots, it does seem like you can put as much velocity on them as you want, and still get darn good performance. Like that Doubletap .45 ACP (not super, amazingly) load, 1010 fps on a 230 grain bullet; .95" expansion and 15.25" penetration!

Makes me wonder why Cor-Bon doesn't use Gold Dots for their loadings; whatever brand bullet they're using do not hold up well at all at the high velocities.

 

[coylh]

The data has everything from 90-158 grain. I found a 180 grain result, but it didn't have expansion data unfortunately.

The three fliers are:
124 grain@1192, 12.2" .79
124 grain@1183, 11.1" .81
124 grain@1181, 11.6" .78

 

[Toejam]

RyanM,
Energy is always conserved. Energy is neither created nor destroyed. It only changes forms (assuming classic Newtonian physics). In your example, the Universe did not “steal†the “missing energyâ€. The “missing energy†was used to create a non-elastic collision.

There are two types of collisions, elastic and non-elastic. In elastic collisions (think billiard balls), kinetic energy and momentum are both conserved.

Your example is of a non-elastic collision. For a non-elastic collision to occur, some of the kinetic energy must be converted into thermal, chemical or potential energy two keep the two colliding bodies from bouncing off of one another.

For example...
When a bullet and a body have a non-elastic collision, the KE of the system goes down. The Universe does not steal that KE. That KE is converted into thermal, chemical or potential energy as the bullet passes through the body creating a wound channel. Simple High School level Physics .

So when Sean Smith contends that bullets with higher KE have a greater wounding potential, he is correct.

 

[MrAcheson]

Ryan,

Your Wound Volume*Velocity vs. Kinetic Energy chart is actually a Wound Volume vs. Momentum Chart. You just have to divide the velocities out and multiply kinetic energy by two. It does have a better correlation (Rsquared=.6 instead of .3 with kinetic energy).

I find this interesting because I have always been a momentum guy when it comes to handgun rounds. It better approximates effectiveness against soft targets like people. Now harder targets like body armor really does require energy values.

 

[Nightcrawler]

If you read Blackhawk Down, I think there's one instance where a little old man was able to absorb 3 or 4 bursts from an M-60 before deciding to sit down for awhile.

That's the first where I've heard anyone say 7.62x51mm is a "notoriously poor stopper". The worst I'd heard anyone say about was that it provided no significant advantage over .223 inside of 100 meters, which I'm not entirely convinced of, but have not the means to test.

In any case, note that in the incident described in Blackhawk Down, I believe the M60 in question was equipped with 7.62x51mm SLAP rounds. Sabot Light Armor Piercing. Basically, it's a .308 sabot-ed down to a .22 caliber, super-high-velocity, armor piercing bullet.

The evidence I've gathered seems to suggest that a very light weight projectile, even moving at high velocities, will perform poorly, despite having high kinetic energy. Whereas a heavier projectile, moving at slightly slower velocities, will do better.

(230 grain @ 900 fps vs 115 grain @ 1250fps, 147 grain @ 2700fps vs. 62 grain @ 3100 fps).

Hard to say for sure, though. The .308 vs. .223 is actually a poor example, though, as a .308 ball round produces rougly twice the kinetic energy of a .223 round. But, as has been said, KE doesn't translate directly into wounding effect. You can walk up to somebody and shove them with both hands, creating more kinetic energy than any handgun bullet, but you won't kill them.

 

[MrAcheson]

I think this momentum plot really tells the story better. You can clearly see the way the individual calibers band with momentum. There just seems to be a lot of scatter in wounding potential within the data that is effecting the spread.

The curve fit is wound volume = 5.532 * momentum incidentally.

 

[buzz_knox]

That's the first where I've heard anyone say 7.62x51mm is a "notoriously poor stopper". The worst I'd heard anyone say about was that it provided no significant advantage over .223 inside of 100 meters, which I'm not entirely convinced of, but have not the means to test.

Pat Rogers recounts an incident in which he had to shoot an NVA mutliple times with an M-14 at point blank range to put him down. He shot the guy, went to take out his comrades, had to shoot the first guy again after he'd gotten up, shot a couple more comrades, and then finish the first guy off with a couple more rounds.

Also, on www.tacticalforums.com, there is information that standard M80 7.62 mm ball is not as effective as the caliber and power would lead one to believe.

 

[Graystar]

I don't know that 'energy transfer' is a significant factor with handgun bullets. You want tissue damage and severed blood vessels.

I think they’re the same. Like the race car that completely destroys itself to save the life of the driver, energy is transferred by destroying tissue.

Federal EFMJ in .40...is there really anything more to discuss??

 

[buzz_knox]

Federal EFMJ in .40...is there really anything more to discuss??

Only that the EFMJ isn't working as advertised, in that it's not as effective as Federal and others led us to believe it would be.

 

[Graystar]

Only that the EFMJ isn't working as advertised, in that it's not as effective as Federal and others led us to believe it would be.

Really? In what way are they not effective? Is there someplace online I can read up on it?

When I heard they expanded reliably I just loaded them into my Glock and haven't thought much of them since, so I'm a tad behind in the latest news.

 

[buzz_knox]

Check on www.tacticalforums.com. There have been some discussions about lack of expansion with the .40 EFMJ Detroit is issuing.

 

[RyanM]

[/QUOTE]

Energy is always conserved. Energy is neither created nor destroyed. It only changes forms (assuming classic Newtonian physics). In your example, the Universe did not “steal†the “missing energyâ€. The “missing energy†was used to create a non-elastic collision.

That's pretty much exactly what I said. "the rest of the energy is converted into heat, vibration, noise, etc." I also said "in simplest possible terms," remember. Every time I try to explain how energy works in collisions to people face-to-face, I get extremely blank looks, and sometimes some drool. But "the universe stole it" and "only the energy that tags along with the momentum" are phrases that people can understand.

Your Wound Volume*Velocity vs. Kinetic Energy chart is actually a Wound Volume vs. Momentum Chart. You just have to divide the velocities out and multiply kinetic energy by two. It does have a better correlation (Rsquared=.6 instead of .3 with kinetic energy).

I find this interesting because I have always been a momentum guy when it comes to handgun rounds. It better approximates effectiveness against soft targets like people. Now harder targets like body armor really does require energy values.

Oh yeah, not sure how I missed that, cool.

And actually, it's pressure that matters more when piercing soft body armor. Tensile strength and all that, remember? Though I believe pressure can be [iroughly calculated by V^2 times some other stuff (I think mass actually cancels out at some point), so it correlates with energy a bit.

I also remember reading a study on the size of the bruise a non-penetrating bullet will make through soft body armor, and momentum correlated the best.

In any case, note that in the incident described in Blackhawk Down, I believe the M60 in question was equipped with 7.62x51mm SLAP rounds. Sabot Light Armor Piercing. Basically, it's a .308 sabot-ed down to a .22 caliber, super-high-velocity, armor piercing bullet.

I keep hearing that claim, with zero sources ever given. Everything I've ever read about SLAP rounds suggests that they were only ever issued for M2s, and the 7.62mm SLAP rounds never left the laboratory. http://www.fas.org/man/dod-101/sys/land/slap.htm

Background: During the 1980s, the Marine Corps invested in both .50 caliber and 7.62 x 51 SLAP concepts. The .50 caliber effort was very successful and extends the light armor capability of the M2 Heavy Machine Gun significantly. The 7.62mm effort was not successful in the M60 and caused catastrophic barrel failures due to in-bore break-up of the sabot and the penetrator puncturing the side of the barrel. Also, its increase in penetration was not on the same order of magnitude as the .50 caliber SLAP's.

There is the M993 AP round, which uses a sub-caliber tungsten penetrator, but the penetrator is encased in the jacket, no sabot to speak of. http://www.fas.org/man/dod-101/sys/land/762ap.jpg

 

[Graystar]

There have been some discussions about lack of expansion with the .40 EFMJ Detroit is issuing.

Thanks for the link. I'll have to research it some more, but I’m not ready to condemn the round yet because of a failure to penetrate a metal plate in someone head, especially when we don’t know the deflection angle. And one out of 11 didn’t penetrate winter clothing? Well I’ve got 20 in my G17 so that ratio works for me!

I did hear that there were some early lots that had quality problems, but I heard Federal had straightened those problems out. In any case I think that ultimately they will be better performers than hollowpoints. But that’s just my own opinion, valued at what you paid for it!

 

[MrAcheson]

And actually, it's pressure that matters more when piercing soft body armor. Tensile strength and all that, remember? Though I believe pressure can be [iroughly calculated by V^2 times some other stuff (I think mass actually cancels out at some point), so it correlates with energy a bit.

In hard targets you have to worry about fracture mechanics (crack propogation and the like) that aren't as important with squishy elastic stuff like human tissue. Those mechanisms are better modeled with energy.

 

[coylh]

These gelatins tests are giving me a headache. I don't think this Hole Volume theory explains the real world results well. Look at this data.

Bullet type Weight Velocity Penetration Final diameter Energy Hole volume Source of data
12 guage 437 1513 14 0.78 2220.88566 6.689707397 http://home.snafu.de/l.moeller/Zielwirkung/Frog.html
.30-30 Silvert 170 2020 17.5 0.66 1539.992363 5.9870902 http://home.snafu.de/l.moeller/Zielwirkung/Frog.html
.357 JSP 125 1390 14 0.7 536.1749505 5.387831401 http://home.snafu.de/l.moeller/Zielwirkung/Frog.html
9mm gold dot 124 1192 12.2 0.79 391.1479899 5.980037324 http://www.firearmstactical.com/test_data/9mm/geo9-124+p-g26.htm
.40 Hydrashok 165 943 18.25 0.63 325.7423585 5.688972692 http://www.firearmstactical.com/ammo_data/40s&w.htm
.30-06 SP 150 2923 16.38 0.56 2845.219632 4.034408153 http://home.snafu.de/l.moeller/Zielwirkung/Frog.html
.44 mag Fed 240 1180 20.4 0.55 741.89452 4.846692066 Street Stoppers

The chart shows each load paired with Ryan's Hole Volume index. The labels correspond to the data points going left to right. This index looks really flawed for it to score such different loads so similarly.

BTW, if anyone knows where you can find more gelatin tests with this kind of data, could you let me know; I can't find any more searching the web. Speaking of gelatin, has anyone else noticed that the penetration of the calibration BB is not even close to consistent in a lot of people's tests?