So, a question on .40 S&W bullet weights, and the resulting suggestions brought up a question. It wasn't relevant to the topic, so I started a new one.

In terms of penetration, which one would penetrate further, assuming the same muzzle energy (not velocity)? A 200gr jacketted hollowpoint or a 180gr jacketted soft point?

Well, if you keep muzzle energy constant and reduce bullet weight, velocity has to increase. I am sure they would have to be loaded differently to get an equal muzzle energy from a lighter bullet, but this would yield an even higher velocity.

Correct me if I am wrong, but I believe that JSPs typically penetrate better than JHPs anyways simply due to slower expansion. Combine this with a higher velocity and that equals more penetration.

Higher velocity can mean less penetration depending on the equation below.
The higher the velocity the more resistance placed on the bullet at impact.
You can’t take any of the following out of the equation in regards to terminal ballistics.

Mass, bullet design, velocity and material penetrated are all co-equals in the equation.

If you take two identical bullets and drive one at 900fps and the other at 1400fps the one at the higher velocity may penetrate somewhat less.
But that doesn’t mean either is less suited for any particular target.

In your case I believe the JSP would penatrated deeper due to design and the weight differance only being 20gr.

K.I.,

If two bullets have the same design and shape and the same muzzle energy, the one with greater momentum will penetrate furthest. M882 9 mm ball and M1911 .45 ACP ball are an example. They have the same basic shape and construction and are driven at very close to the same muzzle energy. The .45 has about 45% more momentum and penetrates ballistic gelatin about that much further.

When you start comparing two different bullet constructions, as your question does, you run into the problem that the two will have different relative behavior at different impact velocities and in different target materials. For example, for a long enough shot into a nice uniform medium like ballistic gelatin, the hollow point can impact at low enough velocity to fail to expand at all. Then it will penetrate like a solid, in which case it can out-penetrate the softpoint by a percentage roughly proportional to their momentum difference at that range, as outlined above. At shorter range, the reverse would be true, assuming enough starting velocity to expand the hollow point.

In real world situations, hollow points sometimes expand and sometimes don't, depending on what clothing or hide or whatever else they run into on their way into the target? So, in real world targets, sometimes the hollow point will penetrate less and sometimes more. Unfortunately, that's as close as a generalization on the matter can come. That unpredictability is why I personally gave up on bullets designed to change shape on impact. Flat meplat solid shapes perform very well and much more consistently.


5150,

I still want to see the equation itself and not just the factors that apply on either side of the equals sign. That takes us right back around to the same problems involved in trying to create a realistic stopping power formula. 'All else' is never equal, so, I don't think we'll ever get the real-world data needed to create a good one. I keep hoping, though. I expect successful computer modeling of bullet designs interacting with living bodies will become available before adequate real-world data can ever be collected.

K.I.,
5150,

I still want to see the equation itself and not just the factors that apply on either side of the equals sign. That takes us right back around to the same problems involved in trying to create a realistic stopping power formula. 'All else' is never equal, so, I don't think we'll ever get the real-world data needed to create a good one. I keep hoping, though. I expect successful computer modeling of bullet designs interacting with living bodies will become available before adequate real-world data can ever be collected.


According to Dr. Martin Fackler their is in fact a mathmatical formular that models (predicts) the out come and matches Dr. Facklers acctual findings through thousands of rounds of testing. The fomular was created by Duncan Mcphearson.


http://pw2.netcom.com/~dmacp/index.html


This is a review of the book "Bullet Penetration" modeling the Dynamics and Incapacitation Resulting From Wound Trauma, by Duncan McPhearson


<TABLE cols=1 width="75%"><TBODY><TR><TD>This review, written by Martin L. Fackler, MD, appeared in the January 1995 issue of Fighting Firearms and is reproduced with the kind permission of the International Wound Ballistics Association.
This remarkable book by Duncan MacPherson advances wound ballistics to the status of a mature predictive science. One must consider the normally slow growth evidenced in the history of scientific methods and ideas to appreciate the significance of this achievement. We have had a valid tissue simulant with which to do bullet testing that is applicable quantitatively to the human body for only a dozen years: for only half that time has this tissue simulant been used widely in a way that gives comparable results ("BB" penetration calibration of each block).
Bullet Penetration unveils MacPherson's unique mathematical predictive bullet penetration model which he derived from the general equations of motion. He used the methodology described above for experimental shots with various projectiles into calibrated 10% gelatin to validate his model and determine its empirical constants.
Several years ago, when Duncan MacPherson tried to explain to me the necessity for a mathematical bullet penetration model, I didn't understand why it was needed or how it might be applied. If I had any question about the effectiveness of a new bullet I would just shoot it into 10% gelatin and measure the results. I didn't even have to do gelatin shots to answer most of the questions I was asked about bullet performance. I could usually make a pretty accurate estimate by mentally comparing the bullet in question with the results of the several thousand bullets I had already tested. Finally, after MacPherson's experimental verification of his model was nearly finished, it dawned upon me that his predictive penetration model does essentially the same thing as my experience based estimates did -only his model does it more accurately and it can be applied to a far wider variety of questions. It puts the equivalent of more than a decade of systematic bullet testing experience at the fingertips of any intelligent reader who is willing to think the model through.
MacPherson derived his model using the rigorous mathematics and physics required for scientific accuracy: this derivation is included in a 35 page chapter that will satisfy the most critical mathematically oriented reader. MacPherson's writing style and vocabulary, however, make the basic principles and results understandable to the layman.
MacPherson has included an outline of the contents of his book's chapters in the introduction, as well as providing an excellent summary at the end of each chapter. He exposes and corrects common fallacies -- such as the presumption that kinetic energy determines bullet effect. In that section we find:
Newton's laws of motion describe forces and momentum transfer, not energy relationships
Damage is done by stress (force), not energy.
Stresses cause damage only if they strain body tissues above their elastic limits. Most expanding handgun bullets simply waste the kinetic energy used in producing the small temporary cavities they cause.Included is an excellent clarification of statistics for the layman. It explains how the seemingly plausible collection of data from shootings is immensely compounded by the large number of variables; that any claim that incapacitation from bullet hits can be assessed within a few percent based on shooting data "is based on ignorance, or fraud, or both." This easy to understand primer on statistics should enable the layman to avoid being misled by data that is "too good to be true."
Although MacPherson derives his penetration model with the rigor necessary to satisfy the most critical professional scientist. he also provides graphs derived from the model to enable the interested layman to apply the information easily. For example, his model permits the interested reader to obtain the maximum in accuracy from bullet testing in ordnance gelatin. Calibrating each gelatin block with a "BB" shot (at 590 ft/s) gives a quality control check, but within the calibration standards (+/- 1 centimeter of the 8.5 cm standard penetration depth) there can be a variation of +/- 12% (and many laboratories are reporting shots in which the BB penetration does not meet these standards). From MacPherson's graphs the reader can obtain the adjustments to normalize results to the standard 8.5 cm even if the calibration shot was several cm from the 8.5 cm standard. This normalization of experimental results cuts out a large source of potential error, that has heretofore been overlooked, and allows more accurate bullet performance comparisons.
MacPherson includes graphs that allow the reader to obtain a realistic approximation of bullet penetration in gelatin from bullets recovered from shots into water. The expanded bullet's diameter, weight, caliber, and velocity, plotted on the appropriate graph, allows the reader to read off the equivalent penetration depth in 10% standard gelatin (calibrated to a "BB penetration depth of 8.5 cm.)
The photographs relating striking velocity to deformation and expansion for various cast lead projectiles and jacketed expanding handgun bullets should prove exceptionally useful to those who experiment with, or are interested in, bullet
design -- or are just interested in understanding better what they have seen in their own experimental work or that of others.
MacPherson's credentials are impressive to say the least -- he is, in fact (no joke), a rocket scientist -- whose accomplishments include developing a new guidance technique and the equations that were used to guide the Mercury astronauts into orbit. He is now a busy consultant in space flight with an impressive clientele. Duncan has had a lifelong interest in firearms as a shooter and experimenter and has read widely in the field. He demonstrated the depth of his insights into bullet effects when, in 1976, he published "Relative Incapacitation BULListics." That article analyzed and pointed out the fatal flaws in the now infamous Relative Incapacitation Index (RII). The National Institute of Justice NIJ, originator of this ill-fated bullet rating scheme, disregarded MacPherson's well-founded criticisms. in 1986, two FBI agents had to die, unnecessarily, (in the Miami shootout) to prove to the world that MacPherson was entirely correct when he pointed out, ten years previously, that the RII was seriously flawed.
The strongest focus of MacPherson's work is on getting the maximum efficiency out of the inherently limited handgun. He discusses accuracy, recoil, calibers. bullet types, bullet velocities and bullet weights; relating all of these to his wound trauma incapacitation model (which is his penetration model with human anatomy, physiology and psychology and other considerations added).
This superb book can provide those responsible for weapon and bullet selection with the reliable information they need to make informed choices -- to balance intelligently the inevitable pros and cons that accompany these compromises. It further provides data and insights that are of crucial importance to Wound Ballistics Researchers, Forensic Pathologists. Firearms Examiners, Trauma Surgeons, Ordnance Engineers, Law Enforcement Personnel and others critically dependent on firearm performance.
MacPherson's book is a scholarly scientific work. It is not for those who prefer their facts predigested and spoon fed -- it is for mature minds that are willing and able to think for themselves. Rather than just doling out answers, MacPherson gives his readers the tools they need to figure out the best answers to their own particular bullet-effect-related problems for themselves. Martin L. Fackler, MD <CENTER>

http://pw2.netcom.com/~dmacp/Fackler_review.html</CENTER>
</TD></TR></TBODY></TABLE>

Dont need to get worked into a headache just follow the advice of Elmer Keith, heavy flat nosed bullets at all the velocity you can tolerate.

All things being equal with expanding bullets... Well.... that's the one thing you'll never get. With expanding handgun bullets against meat & bone, the only constant is the overwhelming lack of constants.

How folks draw conclusions from that is beyond me. :D

I have MacPherson's book. It does, indeed, model bullet penetration and total mass crushing disruption in ballistic gelatin, and even contains skin penetration tests. However, as MacPherson himself says in the introduction to Chapter 5, Tissue Simulation:"One of the issues making demonstration of bullet effectiveness so intractable by either test or analysis is the inhomogeneity of animal (including human) bodies. Even minute differences in impact location can alter the tissues in the bullet wound track and produce WTI {Wound Trauma Incapacitation} changes that are larger than those due to the bullet physical and dynamic parameters."MacPherson goes on to say that a homogeneous test medium is necessary to avoid real tissue structure variance giving one bullet a false advantage in the results over another. The simulant's consistency insures you are comparing apples to apples. MacPherson does not, however, present a way to model the probability that a bullet will strike a point where its ranked performance in the simulant will be born out in practice. It is simply the best available method of bullet evaluation in the laboratory environment at this time. It may be pretty good in the real world, too, but how good is difficult to ascertain for the reasons MacPherson himself outlined in that introduction.

At one of my Gunsite classes a student who had been on safari showed us his video of the trip. He had shot a bull buffalo (syncerus caffer, which always appears to me to be to the American bison what a pit bull is to a poodle). He was firing 500 grain Hornady solids in a .460 G&A rifle, modeled after Jeff Cooper's "Baby". It took a number of rounds to stop the beast, who ran into dense cover to try hide well enough to ambush the hunters when they came after him. These critters are very aggressive, and he got close to succeeding, too, as I recall, except that they could smell him as they got close enough. Not a lot of warning. In any event, once the animal was really down (total of 4 hits at that point, IIRC), the hunter slowly closed in on it and fired a head shot just to make sure it wasn't going to jump back up and charge. He later had a picture of the recovered bullets, including the head shot bullet. That copper solid had bent in the middle as it deflected off the skull. It penetrated the skin and scooted around under it, if that counts for anything, but that was all.

Meanwhile, this fellow's wife took her buffalo with one shot. It was sunning itself of a small island. She fired a .404 Jeffery over tall grass from standing in a narrow punt canoe, knocking herself over into the water in the process (but keeping the rifle above her head and dry). Some guys have all the luck with women.

Now I don't suppose the .404 Jeffery (also known as .404 Rimless Nitro Express and Jeffery 10.75x73) out-performs the .460 G&A in gelatin. I also don't know how this fellow’s wife would have fared firing the bigger gun from where she stood? I don't know what the human control probability of hitting the right place was with her gun vs. his? Had she simply done a better job of picking a gun she could control? Did he have worse "buck fever", or just worse luck?

My point in relating this tale was to describe that final coup de grace head shot. It is an extreme example of how, in real-world conditions, there are events that demonstrate thresholds, below which little or nothing of significance happens. Proportional performance in gelatin does not measure that, as it has no cutoff point for anything moving fast enough not to bounce off the face of the gelatin block. It also doesn’t give a big jump in rank to bullets that can break through the average bone and keep going, which I think a real-world stopping power ranking would have to do. It means a real world ranking formula would have a discontinuity at the jump, and the elements of the formula that determined that threshold would be different for every target. If you wanted to hunt syncerus caffer, you would need to look him up on a table of coefficients for different critters and plug his numbers into the equation.

If the equation is ever worked out, it ain’t gonna be pretty.

Meanwhile, I may not know no better, but I'm with Bill M and Rrider. The KISS principle in action.

UncleNick, You never cease to amze me with your vast amount of knowledge. I always enjoy reading your posts...

yeah


all else being equal the bigger bullit always wins

The original question was a 40 caliber 180gr JSP vs. 200gr JHP
I still conclude that based on bullet design in this case the JSP will penetrate deeper than the heavier 200gr JHP. The JHP will expand much quicker and possible larger than the JSP thus subjecting it to more resistance.
Even if you increased the velocity of both the results would be the same.
And in this case the bigger bullet would not win in regards to penatration.

You are making a huge assumption that may or may not be true... Whaqt if niether of mushroomed, then which one do you believe will out penetrate the other?

If both bullets functioned as designed was factored into my thoughts.
Its all hypothetical anyway.

UncleNick, You never cease to amze me with your vast amount of knowledge. I always enjoy reading your posts...


I agree! So much knowledge to try to absorb , thanks for taking the time to share with all of us here!