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Old October 5, 2012, 04:59 PM   #1
Coltman 77
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Definitive SD Ammo Data

There are constant threads here regarding the best defensive ammo available for handguns and rifles.

Let's cut out the speculation and get to some hard, verified data.

Here's a link that covers it and should be made a sticky thread IMO.


http://ammo.ar15.com/project/Self_De..._FAQ/index.htm


BTW, Mods if a thread like this already exists, I can't find it and it needs to be made very upfront IMO. Thanks.
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Old October 5, 2012, 05:48 PM   #2
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Much of the content in the link that you've provided came from here-

http://www.m4carbine.net/forumdisplay.php?f=91

and here

http://www.m4carbine.net/showthread.php?t=19887

-and might be of interest to those researching the topic.
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Old October 6, 2012, 04:48 AM   #3
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Quote:
Let's cut out the speculation and get to some hard, verified data.
The information is good, but has the same problem as all the other information and so does very little to cut out speculation. It doesn't tell you if the bad guy is going down or not. In fact, lacking is a huge amount of real world data (with its own limitations) and reliance on simulations is hardly what could be considered hard, verified data for when it comes to predicting whether or not a person is stopped.
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Old October 6, 2012, 12:06 PM   #4
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Your mistake is that you assume there is such a thing as definitive data. While I respect Dr. Roberts, his is but one voice in a field containing many and there is very little consensus within that field.

Dr. Roberts' work, along with others like Duncan MacPhearson, Shawn Dodson, and the FBI, is based heavily upon that of Dr. Martin Fackler. Unfortunately, many if not most of the "experts" whose opinions are based on the work of Dr. Fackler take his conclusions to logical extremes and fail to explain, or perhaps even understand, how and why Dr. Fackler came to those conclusions to begin with.

For example, many want to discount temporary cavitation, and by extension kinetic energy transfer, all together because Dr. Fackler said that it was an unreliable wounding mechanism at handgun velocities. What seems to be lost, however, is that just because something is unreliable that does not mean that it is non-existant.

The reason, according to Dr. Fackler, that temporary cavitation is unreliable with handguns is that many tissues in the human body are too elastic to be significantly damaged by the temporary cavitation produced by most common handgun cartridges. Dr. Fackler does, however, qualify that statment by noting that certain tissues (he uses liver tissue as an example) are very inelastic and can be damaged by handgun-level temporary cavity. Dr. Fackler has also done very little work with the more powerful handgun cartridges like .41 Magnum, .44 Magnum, and .454 Casull that generate much more kinetic energy and, with careful bullet selection, much larger temporary cavities than most common handgun cartridges do.

Another example is the almost pathological fear of bullets which fragment. Because Dr. Fackler generally admonishes against fragmenting handgun bullets, many seem to feel that anything less than 90% weight retention is completely unacceptable. What is lost is that the reason Dr. Fackler admonishes against fragmenting handgun bullets is because they typically display lackluster penetration. This is not, however, universally true as there are some bullets that can fragment significantly without sacrificing adequate penetration and, if the fragmentation occurs deep enough with large enough fragments, it can actually increase the bullet's wounding potential. An example of this is the semi-jacketed hollowpoints often found in revolver cartridges like .357 Magnum. A 125gr .357 Magnum SJHP will quite often shed is jacket in large shards while the lead core continues to penetrate 11-13" while retaining 60% or more of its weight.
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Old October 6, 2012, 12:47 PM   #5
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Quote:
Originally Posted by webleymkv:
Dr. Roberts' work, along with others like Duncan MacPhearson, Shawn Dodson, and the FBI, is based heavily upon that of Dr. Martin Fackler. Unfortunately, many if not most of the "experts" whose opinions are based on the work of Dr. Fackler take his conclusions to logical extremes and fail to explain, or perhaps even understand, how and why Dr. Fackler came to those conclusions to begin with.

For example, many want to discount temporary cavitation, and by extension kinetic energy transfer, all together because Dr. Fackler said that it was an unreliable wounding mechanism at handgun velocities. What seems to be lost, however, is that just because something is unreliable that does not mean that it is non-existant.
I never got that impression from reading some of their works.

In fact, MacPherson states on pages 7 and 8 of "Bullet Penetration"-

Quote:
"Any attempt to derive the effect of bullet impact in tissue using energy relationships is ill advised and wrong because the problem cannot be analyzed that way and only someone without the requisite technical background would try. Many individuals who have not had technical training have nonetheless heard of Newton’s laws of motion, but most of them aren’t really familiar with these laws and would be surprised to learn Newton’s laws describe forces and momentum transfer, not energy relationships. The dynamic variable that is conserved in collisions is momentum; kinetic energy is not only not conserved in real collisions, but is transferred into thermal energy in a way that usually cannot be practically modeled. The energy in collisions can be traced, but usually only by solving the dynamics by other means and then determining the energy flow.

Understanding energy and how it relates to bullet terminal ballistics is useful even though energy is not a useful parameter in most small arms ballistics work
.”
And Schwartz states on page 7 of "Quantitative Ammunition Selection"-

Quote:
"While a projectile in motion possesses both momentum and kinetic energy, the penetration of a transient projectile through a homogenous fluid or hydrocolloidal medium constitutes an inelastic collision mandating that it be treated as a momentum transaction. Therefore, a momentum-based analysis of projectile motion is the most equitable approach in constructing a terminal ballistic performance model.

Although it may be possible to devise a mathematical model based upon the expenditure of a projectile’s kinetic energy as it traverses a medium, there is nothing to be gained from the pursuit of such an unnecessarily complex approach
."
From what I can tell, it appears that neither is saying that KE transfer doesn't count, but rather that KE transfer is just not a very feasible/efficient way to analyze the problem.

Does that make sense the way I said it?
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Old October 6, 2012, 01:28 PM   #6
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I wasn't referring to MacPhearson specifically with my comments about failing to understand/convey Fackler's rationale, I was only using him as an example of someone whose work is based upon that of Fackler such as Dodson, Roberts, or the FBI.
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Old October 6, 2012, 01:30 PM   #7
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Oh, yeah, I know- I was just responding to your statements regarding the seeming dismissal of KE transfer.

Didn't mean to infer that you were singling out anyone in particular.

I also agree with you when you said-

Quote:
Originally Posted by webleymkv:
"Another example is the almost pathological fear of bullets which fragment. Because Dr. Fackler generally admonishes against fragmenting handgun bullets, many seem to feel that anything less than 90% weight retention is completely unacceptable. What is lost is that the reason Dr. Fackler admonishes against fragmenting handgun bullets is because they typically display lackluster penetration."
Your opinion agrees with what I've read elsewhere, namely on page 69 of "Quantitative Ammunition Selection"-

Quote:
"When an expanding projectile design is driven at a velocity that exceeds its capacity to sustain the deformation produced by the corresponding increase in hydraulic forces, radical expansion may cause the projectile to lose significant mass through excessive fragmentation. A loss of just ten percent of a projectile’s initial mass in conjunction with an inordinate increase in its frontal area (radical expansion), can result in a significant reduction of the projectile’s terminal penetration and permanent wound cavity mass."
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Old October 6, 2012, 01:33 PM   #8
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Cool, definitive data means no further discussion of this topic will ever be needed.
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Old October 6, 2012, 03:29 PM   #9
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i choose 115 gr gold dot no +p gimmick for my glock 19. im more accurate with this. nice grand canyon wound channel and 17 1/2 inches of penetration.

http://www.youtube.com/watch?v=v2s82NCLKQI
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Old October 6, 2012, 04:15 PM   #10
Coltman 77
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Sparks wrote:

Quote:
Cool, definitive data means no further discussion of this topic will ever be needed.
I respectively disagree, it should actually raise the level of the discussion.

For example, there are some very knowledgeable posts in this thread.

But compare that to this thread full of speculation and personal opinions:

http://thefiringline.com/forums/showthread.php?t=502917
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Old October 6, 2012, 04:17 PM   #11
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I was joking, but you probably couldn't tell. That's why I winked.

It is an interesting and informative thread, and the debate about this will never end. I know that.
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Old October 6, 2012, 04:44 PM   #12
Coltman 77
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Sorry I didn't notice the wink.

Appreciate the nice response.
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Old October 6, 2012, 06:18 PM   #13
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Winkie or not, I thought Sparks' comment was pretty funny.
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