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Discussion Starter · #1 ·
Hi All,

I thought some of you may be interested in this thread at The High Road:

http://www.thehighroad.org/showthread.php?t=293266

The gent who started the thread has been keeping a spreadsheet on the ballistics of many, many different rounds. Most look like factory data, and I don't see any terminal performance stuff, but it's useful just the same.

Enjoy!

Josh <><
 

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From what I saw the data is limited to what the factory claims, for instance the Hornday 9x18 is tabulated at 1,000 fps but nobody ever sees it go faster than 930 or so.

- As kind of an aside to that problem, I'm told the factories use a somewhat standard length barrel for testing - in the case of the 9x18, it's longer than any pistol manufactured for the bullet. That throws off factory velocity claims.

I do like his format and can appreciate the time he took putting it together. Thanks for the post.
 

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I have been fooling with mathematical models ever since I first realized the kinetic energy figures in ammo ads meant absolutely nothing. First I did them on a Frieden electric adding machine then later on a Craig digital calculater - that cost me $250 used (tells you something about the date...my first car cost me less!).

These days it is easy to do up an Excel Spreadsheet with the various theorum for comparison and if one want to kill time that is fine.

The problems are: 1. math cannot really express this (MacPherson's formula, the most educated I have seen has 29 factors needed) and 2. none of it takes into account the two biggest variables; the subject and what you hit inside the subject. That far out weighs any physical properties of the bullet.

The best we can hope for a is a general trend that might tell us + or - 25% and that just is not good enough.

Anyway if there is any interest I can point you to some simple formulae like Taylor Knock Out values, Hatcher, Cooper Short Form or a few others.

Personally, I dont put much stock in any of them. How you shoot makes a lot more difference that what you shoot, though I have certainly seen cases in which good shooting could not overcome poor bullet selection.

Onward,

Jim H.
 

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I agree with Jim that the mathematical models are useless. I'm just not as politically correct as he, nor am I concerned about stepping on anyone's pet theorem.

All the mathematical models either ignore or minimise the most important factor because it CAN NOT be quantified. That is the psychological response of the individual to being shot. That too is subject to a vast array of equally unquantifiable variables.
 

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Discussion Starter · #5 ·
When it comes to mathmatical models, I believe they're useful for comparing aspects of different rounds, but I agree that they're mostly useless.

I prefer to use E=M*V^2, just because it's nice, simple, and proven. A close second is TKO. But, mainly, it's for comparison purposes only. Too many variables, including some we just don't know about yet. For example, I believe that dwell time in the target has a great effect on the target. I can't prove this; it just seems right.

The table I directed you to has, IIRC, just the factory stuff as Nbender stated. It's nice to see it all in one place.

Josh <><
 

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Actually, kinetic energy has been absolutely disproven as a measure of ballistic effectiveness. All one needs to do is get the book: Bullet Penetration: Modeling the Dynamics and the Incapacitation Resulting from Wound Trauma; by Dr. Duncan MacPhereson (who wrote the guidance programs for the mercury and gemini programs).

It is deep math but it explains why kinetic energy not only has very little to do with incapacitation it leads one in the wrong direction often times. At best though it is just irrelevant.

There are certainly conclusions MacPhereson makes, without good information, in judging the works of others, which sour me on the work but I was at least able to follow the discussion on modeling. I did have to read it three times to really get it though.

Oddly enough, even though he works through his model in excruciating detail, the good Dr. (a PHD in this case) then sort of ignores his own theory and explains why the topic is so hard and in the end just seems to conclude that there is no substitute for mass and size. But at the same time those will not make up for poor shot placement.

It is a curious blend of highly sophisticated math and a bit of common sense.

Odly enough, my college physics book contains the same information in a consise sentance and goes something like: "In a colision kinetic energy does not matter...a feather is never dangerous" (I might actually disagree a little with the last part but it is a good point).

Of course the above is strictly scientific theory, the water surrounding the topic of terminal ballistics is so muddy that one could easily buy into just about any mathematical model.

Onward,

Jim H.
 

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Discussion Starter · #7 ·
Mr. H,

I just use it because E=MC^2 seems to have served the folks responsible for the atom bomb very well.

I have a very hard time believing that something the size of, say, a piece of sand moving at 10,000fps would not be harmful. Heck, we're concerned about micrometeors when it comes to space travel. I forget the exact speed, but at a certain speed a grain of stellar dust could blow through an Apollo capsule.

I just pretty much figure one mathmatical model is about as good as the next, and go with what I'm familiar with.

Josh <><
 

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Josh, your example, grain of sand versus Jim's feather neglects to consider density. a feather has a lot of surface and not a lot of density. A grain of sand in comparatively dense with relatively little surface. It makes a BIG difference.

There is nothing wrong with mathematical models from a purely physics standpoint. There is when one is considering self defense shooting performance. That is because, as I said before, they either ignore or minimise the personal psychololgical factor which can not be quantified. Taylor, Hatcher, et al - if they consider psych factors at all, stereotypically make suppositions in their formulae that work in the theoretical world that are not truly applicable to the real world.
 

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While it was not Dr. MacPherson who pointed this out, it does dovetail with his explanaition of the irrelevance of energy, when someone used the example that the body absorbs hundreds of times the kinetic energy of a 30-06 during laser surgery.

MacPhersons example also involves a 30-06 in that he states the main effect of the kinetic energy transferred to the target has the net effect of raising the tempreture of the target a few hundreths of a degree...it is force that is at work in incapacitation not energy. But there are so many complicating factors a mere measurment of force (which is directly related to momentum) would be naive.

I am not a rocket scientist (he is) but I do get his argument.

Even for us non rocket scientists it is easy to disprove the relevance of energy...shoot a bowling pin with a .357 magnum. A bowling pin weighs 4 lbs. A .357 should knock it 100 feet straight up if you shot it from underneath! Even if you allow for friction loss, it should go more than the 2 or 3 feet it will actually lift one. Instead, what we find is that rounds with less energy can actually lift or push the pin further.

High velocity rounds do indeed tear up meat and move fluids around impressively...but it not due to their energy. At least according to the rocket scientist.

The point is moot, no numbering system seems to get the job done because we dont have a truly scientific way of confirming the results...but one must take care he does not adopt something that leads him in the wrong direction.

Just ramblin, and hoping that the 30+ years I spent crunching numbers was not totally wasted, even if I did only find what does not work ;)

Jim H.
 

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Hmm... I guess I am going to have to look at some of these references, cuz I r confused. ???

"it is force that is at work in incapacitation not energy"

Huh?

Force and energy are not separate things. Energy is required to make force, specifically, F=m*a, or Force = mass times acceleration. You need potential energy, in the form of gunpowder, converted to kinetic energy when it is burned, to produce the gasses that produce the acceleration.

I certainly believe that the energy contained in cartridge is not enough to knock anyone down, or otherwise every time I shoot I'd end up on my butt. If you pounded the bullet out flat enough to make a 4 foot square sheet, and sent it down range with the same energy (disregard air resistance for a moment), I expect all you would get is a sheet of lead or copper foil wrapped around your opponent. Wouldn't knock him down ( might distract him for a moment tho!).

However, there has to be enough energy to make the bullet exit the barrel, fly downrange, enter our felonious opponent, expand (maybe), and travel through his anatomy far enough to damage things like major blood vessels and the central nervous system.

Since the energy-- or force -- of the bullet is not enough by itself to knock someone down, you have to place it where it tears up something that will require the felonious one to go down, via loss of blood or destruction of CNS components. I think this is the key to incapacitation. You need enough energy (and accuracy) to make the bullet do this.

It does seem that when you move up to rifle velocities, you start getting effects that are not solely due to pushing a small hole through key parts of the body. Animals and people shot with rifles (in other than CNS locations) generally seem to be considerably less perky afterwards than those shot with handguns. Energy is certainly at the root of this -- whether it delivers such a shock to the nervous system, or is enough to disrupt (temporarily or permanently) key tissue away from the wound channel, I don't know. I am trying to think of who it was I read recently who said that 80% of those shot in the torso with a handgun round survive, but 80% of those shot with a rifle round don't. I am a little suspicious of the exact percentages, but I suspect this is ballpark correct. Consider that a lot of the .30 caliber rifle bullets don't weigh much more than handgun bullets, but their effects are certainly more substantial -- the difference is the energy with which they are driven. Of course with rifles you can get both more mass, and more energy -- and energy is a key part of the equation. Throwing a 400 grain bullet with your right arm is not as impressive as throwing it with a .45-70 Marlin.

Moving up the energy scale, when you shoot things with small amounts of material traveling at very high velocities, you do get some tremendously destructive effects. Kinetic energy penetrators --- a 2 or 3 centimeter (diameter) rod of tungsten or depleted uranium moving at something like 5000 feet per second --- are analagous to small arms rounds. Basically it's a high speed bullet. And they really tear up other tanks. I've been inside the turret of a tank that was shot with a KEP (that is-- I was in it AFTER it was shot!). Very ugly. Besides everything inside being absolutely torn up, there was molten steel embedded in shredded clothing that had been inside the turrent.

(And I believe that if you could hit someone with a feather at 10,000 miles per hour, they would not like it, but the trick would be getting the feather to survive the acceleration. Doubtful!)

Handgun rounds seem to function at level of force whose upper limit is so constrained by the small amounts of mass (bullet size/weight) and energy (amount of powder) that can be put into a handgun that the only terminal ballistic effect you can count on is punching a hole. Any "excess" energy is so little, compared to the size of a human, that it has no measurable effect. The only other variable you can fiddle with is the construction of the bullet itself (e.g. hollowpoints, lead, alloys, copper, whatever).

Like abninftr brought up, the psychological aspect of being shot at is a huge variable that doesn't seem dependent on energy, mass, or even being hit at all sometimes. That combined with all the variables in the shooting situation itself (e.g. barriers, clothing, fat/skinny/muscled people) do make mathematical formulas for incapacition very suspect.

elb
 

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This is why I dont like these discussions. It took me three complete readings to get the good Dr.'s drift on this and there are more than 29 factors in his model of wound trauma incapcitation (but energy is not figured in any of those 29 factors).

There is shear force, verctors and all sorts of stuff abolut viscosity that I dont recall off the top of my head.

But I do recall he made the convincing case in one short section (just as my college physics book did in a short sentance) that while moving bodies possess kinetic energy, and it takes energy to get them moving it does not have anything to do with damaging soft tissue in a causal relationship.

It's not my theory, it is that of others. But I will say, if energy had anything to do with effectiveness then one would be forced to choose a .243 over a .45-70 to stop a charging grizzly since it has more energy (and the bear is going to absorb every ft. lb from the pea shooter since it wont go through)... not this boy!

If one thinks numbers mean something (I dont), then he would be behoved to get the book and study up on the mathematical theory. After reading the book several times I got the impression that Dr. MacPherson was not all that keen on his own model either. He more or less concluded that, given equal bullet design and equal placement a .45 would always be 1.7 times more effective than a 9mm at disrupting tissue.

I have identified 4 mechanisms in which bullets can be used to effect the outcome of a lethal encounter and a minimum of 6 levels of of shooting patterns (each of which can involve the 4 mechanisms either individually or in concert). Add to that the vast diversity of mental and physical attributes of the subject being shot, how many times he is shot, exactly what is hit inside the body, and host of other variables. Any attempt to use a simple mathematical model to predict the outcome of this is doomed from the outset....there are simply too many factors that trump the ballistics in the equation.

I still do not see how numbers are going to help us at all other than the intuitive conclusion that, given equal hits, a bigger hole just might work quicker and an exit hole will let in more air and let out more blood. Transfering some mysterious level of power, no matter how you measure it, does not seem to have a thing to do with it (I do notice that when I hit bone a big bore pistol breaks it up more than a high velocity rifle though - I thought that curious until an orthepedic surgeon explained that a hammer would do even better).

Tis a complex topic and I pulled my hair out trying to figure it out. In the end, all we can do is shoot better and more :-/

Jim H.
 

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This is a hard topic to get a handle on. I find it particularly hard since I spent my life from the time I was a mid-teen researching to find some mathmatical way to measure it (it is in fact the very reason I learned to program computers as early as the late 1970s! - dont let that impress you, the technology rapidly outgrew my abilities).

Anyway, what I learned is what does not work.

If you absolutely have to have some sort of number, Old Grandpa, Josh and Steve are actually on to about the only real figures that matter.... look into their tests of bullets in water and wet newsprint or look into the tests of "calibrated" 10% gelatin on other sites (there is also a new media called the "bullet test tube" that is very interesting).

To be sure, we have learned that what the bullet does to artificial mediums like water, newsprint or gelatin matter not at all (those things are not flesh and blood and are nowhere near as resilliant). However, how big the bullet expands and how deep it goes (to a point) do matter.

If you have to have a number. Then set you up a spreadsheet and record those numbers and calculate the volume of the damage. I would set a cut off point for penetration as how much air you penetrate after exiting the body hardly matters.

FWIW I use the following cut offs: Water 30", 10% gelatin 18", Soaked Newsprint 12". Or at least in those ranges, my mood swings from time to time.

Bear in mind, it is still just a number. The mental and physical characteristics of the subject being shot and the exact path of the bullet matter so much more than that number that ballistics still takes a back seat.

Onward,

Jim H.
 
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