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Defining stopping power (Michael Courtney's thread)

Discussion in 'General Gun Discussions' started by P95Carry, Dec 19, 2005.

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  1. P95Carry

    P95Carry Moderator Emeritus

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    Confession - in process of tidying up a post not needed - lost whole thread.! It happens!

    Let me try and re construct - from cached page pre delete problem.

    First post from Michael Courtenay -

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    Defining Stopping Power

    Many discussions of handgun stopping power are unproductive because they lack a quantitative definition of the stopping power concept. The issue is clouded by potentially complicating factors such as shot placement, intermediate barriers, and the mindset and individual physiology of the target. This post provides a quantitative definition of stopping power that allows one handgun load to be compared with others for a specified shot placement. The ideas presented here are a quantitative definition of stopping power of a given load for any specific unobstructed shot placement and target species, but we have in mind the specific case of involuntary (see footnote 1) incapacitation of human targets shot near the center of the chest.

    It is well known that in the absence of hits to the central nervous system (CNS), handgun bullets do not reliably provide immediate incapacitation, or even reliable incapacitation in the short time span of most gun fights (under 5 seconds). Therefore, any comparative measure of stopping power must be concerned with the probability of a given load to produce incapacitation in a specified time frame for a specific shot placement.

    For instance, we could describe the stopping power of a load as the time interval required to achieve involuntary incapacitation in 90% of the cases where the target is hit with that load at the specified placement. For example, a load that produces incapacitation in 90% of targets in fewer than 8.6 seconds would be considered to be better than a load that requires 12.2 seconds to produce incapacitation in 90% of targets.

    However, the time to achieve a 90% probability of incapacitation is not a complete definition of stopping power. The 90% probability time is somewhat of a worst-case scenario. (See footnote 2.) We might also consider the average time to incapacitate targets with a specified shot placement. A load which produces a 4.7 s average incapacitation time would be considered better than a load which produces a 7.8 s average incapacitation time.

    In addition to 90% incapacitation times and average incapacitation times, we might also consider the 20% incapacitation time, which is something of a measure of how well a load is working in a sort of ?best case scenario.? A load that produces a 20% chance of incapacitation in 2.0 s would be better than a load that produces a 20% chance of incapacitation in 3.8 s.


    Footnote 1:
    For human attackers, there is an important voluntary aspect to how hits with handgun bullets contribute to the probability of an attack being stopped. This voluntary aspect is real and important, but difficult to quantify, so we focus on the involuntary aspects for now. Our definition of stopping power is constructed with sufficient generality to allow for later inclusion of voluntary effects.


    Footnote 2:
    The idea of an absolutely worst case scenario cannot be defined with any degree of statistical rigor. As the sample size grows very large, there is always the possibility of a case that is worse than encountered previously. However, we can rigorously define the idea of worst case if we fix the percentage of cases that is better than the worst case. Here, we choose that 90% of the cases should be better than what we consider the ?worst case.?




    The totality of these ideas can be represented in a mathematical probability curve that describes the likelihood of a given load with a specific shot placement producing incapacitation within a certain number of seconds. Hypothetical probability curves are shown for three different loads in Figure 1. Keep in mind, that it is not our intent to assert that any given handgun load would produce any one of these three curves, only that curves like these would represent substantial quantitative information about the stopping power of a given load for a specific shot placement. Completely describing the incapacitation potential for a handgun load for a given shot placement requires describing the probability curve for all times that are reasonably encountered in the time span of a lethal force encounter.

    [​IMG]

    The three curves shown in Figure 1 all represent the basic idea that a good bullet in a full-sized service caliber handgun delivered with an unobstructed shot near the center of the chest will almost always cause eventual incapacitation of the target. The different curves suggest that some handgun loads might cause incapacitation more rapidly than others, and a means of quantifying and perhaps predicting this is desirable for selecting and designing more effective ammunition. (See footnote 3.)

    All the curves have the same basic features: the probability of producing instant incapacitation is very small, and the probability of eventual incapacitation is nearly 100%. The three loads are distinguished by their differing abilities to cause rapid incapacitation. Load A takes only 2.0 seconds to incapacitate 20% of the targets. Written as an equation, t20% = 2.0s. Load A also has an average incapacitation time close to 4.7 s, and takes 8.6 seconds to incapacitate 90% of the targets. One might also consider the probability of Load A causing involuntary incapacitation in under 5 seconds, because what happens after 5 seconds is irrelevant given the time span of most gun fights. Load A achieves roughly a 60% likelihood of involuntary incapacitation in under 5 seconds.


    Footnote 3:
    This is not to assert that barrier penetration and the possibility of other shot placements should not be an important part of the ammunition selection and design process. We believe that they should. However, from a scientific point of view, it is often necessary to reduce the number of variables in play in order to understand a simplified view of an issue. More complete perspectives can be more accurately built once the science of various simplified views is better understood.



    Contrast this to Load B which takes 3.8 s for an incapacitation probability of 20%, has an average incapacitation time of 7.8 s, and takes 12.0 s for an incapacitation probability of 90%. Load B has roughly a 34% likelihood of achieving involuntary incapacitation in under 5 seconds.

    Also consider Load C which takes 9.1 s to incapacitate 20% of the targets, has an average incapacitation time of 11.0s and has not caused incapacitation in 90% of the targets until 13.4 s. Load C has less than a 1% likelihood of causing involuntary incapacitation in under 5 seconds. In other words, the only way that Load C is likely to be effective in the time span of most gun fights is for the target to voluntarily cease the attack as a result of the shots fired.

    The ?best case?, average, and ?worst case? incapacitation times are summarized in Table 1. The probability of incapacitation in under 5 seconds is listed as PI(t<5).

    t20% tave t90% PI(t < 5)
    Load A 2.0s 4.7s 8.6s 60%
    Load B 3.8s 7.8s 12.2s 34%
    Load C 9.1s 11.0s 13.4s 1%

    These probability curves suggest the possibility of an idealized experiment where the incapacitation time is recorded for a large number of shooting events where the target is hit with a specific load and a specific shot placement. The data from such an idealized experiment could be used to generate the curves in Figure 1 that represent the likelihood of incapacitation within a given time. The hypothetical nature of the curves in Figure 1 do not preclude considering incapacitation probability curves as a valid description of stopping power. In the idealized experiment, loads that produce more rapid incapacitation will produce curves which are further to the left in a graph like Figure 1.

    In all areas of science, real experiments and observations represent trade-offs between an idealized experiment and the practical realities of data collection. (See footnote 4.) In the scientific pursuit of quantifying stopping power, some experimental designs might consider a variety of shot placements or use a success/failure criteria rather than a continuous variable to measure incapacitation. Other experimental designs use a small number of shooting events or perform the experiment on a species other than humans. In spite of these trade-offs, if an experimental design is clearly described (so that the strengths and limitations are understood), and data collection is faithful to the experimental method, we might be able to use results from these sub-optimal experiments to make predictions on the outcome of a more idealized experiment.


    Footnote 4:
    A fundamental aspect of this trade-off is that cost and time required for a certain number of data points scales linearly with the number of data points, but the uncertainty of numerical results is only reduced by the square root of the number of data points. In other words, reducing the experimental uncertainty by a factor of two often requires increasing the number of data points by a factor of four, which is likely to increase the cost and time by a factor of four. Various trade-offs are used to increase the number of data points without a linear increase in cost or time. These include broadening the selection criteria, studying the effect in more accessible/less expensive species, and using more available measures of the effect under study.



    Some authors split hairs by attempting to distinguish ?reliable? incapacitation mechanisms from ?unreliable? mechanisms that only contribute some fraction of the time. However, since no handgun incapacitation mechanism is 100% reliable within the time span of a typical gun fight (< 5 seconds), this concept of reliable eventual incapacitation is an artificial construct with little relevance to the stopping power discussion.

    In any case, if realistic incapacitation probability curves are anything at all like the hypothetical probability curves for Load A, Load B, and Load C, there are some practical implications for surviving gun fights with handgun loads. Even though some handgun loads might perform significantly better than others, there is no magic bullet. Short of a hit to the CNS, even the best-placed handgun bullets require substantial time (compared to the time span of most gun fights) to cause incapacitation in the majority of cases. As we will discuss later, multiple hits might decrease the time to incapacitation, but short of a direct hit to the CNS, multiple hits do not change this basic result.

    Consequently, surviving a gun fight requires more than good shot placement with good handgun bullets; surviving a gun fight requires tangible actions to avoid getting shot during the time interval before incapacitation occurs. Evasive action is necessary, and the significant likelihood that incapacitation is still several seconds away should be sufficient motive for the defensive shooter to be moving rapidly toward cover, or in the absence of cover, at least moving to make for a more difficult target.

    In summary, we have defined stopping power using incapacitation probability curves that describe the probability of involuntary incapacitation as a function of time. We make reference to the specific case of involuntary incapacitation of human targets shot near the center of the chest to help explain the concept. However, our stopping power definition also applies to alternate shot placements. Generalizing this definition to include voluntary contributions to incapacitation, contributions of new incapacitation mechanisms, and the probability of incapacitation with multiple hits is straightforward.

    Michael Courtney
     
  2. P95Carry

    P95Carry Moderator Emeritus

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    Following posts -

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    Apologies again for the screw-up guys!
     
  3. Mr_Moore

    Mr_Moore member

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    My hat is off to you Doctor.

    Brillant argument and conclusion. I am in awe. Your conclusion, if heeded, may save some lives.
     
    Last edited by a moderator: Dec 19, 2005
  4. Preacherman

    Preacherman Member

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    Back in the late 1990's, I put together a one-page handout for my students on the subject of "Stopping Power" - mainly because they kept asking questions, and I couldn't waste time answering the same questions over and over! In the interests of public debate, here it is. Comments and feedback welcome.

     
  5. P95Carry

    P95Carry Moderator Emeritus

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    Useful pointers Peter. :)

    Good to see thread back on track after my ''faux pas'' !:uhoh::rolleyes:
     
  6. cz75bdneos22

    cz75bdneos22 Member

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    somebody need to sticky this one...pronto...awesome post preacherman...i concur, Sir..:)
     
  7. bad LT

    bad LT Member

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    +1 on the "sticky"
     
  8. Michael Courtney

    Michael Courtney Member

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    If you disagree with the clear, scientific definition I have provided above, please explain why the definition I have given is ambigous, invalid, or does not allow for determination or statistical evaluation with any certainty.

    Science has quantitatively evaluated complex problems with many more complicating factors. What is so different about handgun bullet effectiveness that makes it intractable?

    Once stopping power is defined with a valid and quantitative method (as I have done), then there are standard techniques for determining which more easily measured parameters are highly correlated with the valid, quantitative definition of stopping power. Once this is done, relative stopping power can be predicted with some degree of accuracy from more easily measured parameters.

    Please explain where my above defition is flawed.

    I agree. However, I do not believe that this means that there is a fundamental scientific reason why future designs cannot improve to the effectiveness level of shotgun and rifle loads.

    But improvement of any design requires quantitative feedback of effectiveness. If we know which designs are more effective and why, that tells us how to improve future designs.


    A very good point, with which I heartily agree. We do believe, however, that there are cases where incapacitation via blood loss can be as rapid as 5-7 seconds.

    This is what we called voluntary incapacitation, which we believe will be the hardest aspect to quantitatively predict. Anything that depends on the human will cannot be predicted by scientific means with any more certainty than the stock market.

    However, defining stopping power as we have above, we can separate voluntary from involuntary components. (The rules of probability are quite powerful in separating independent contributions to a combined probability.) We can also assign some broad limits on how the voluntary contribution might look.

    If the effect of this "shock" can be clearly seen in the probability curve (because it occurs much earlier than blood loss effects), then we can begin to notice that some loads have a greater tendency to impart "shock" effects than others.

    Have a look back at the graph of probability curves for Load A, Load B, and Load C. Load A and Load B has an early rise so that they cross the 20% and 40% effectiveness thresholds much sooner than Load C. These curves represent the idea that Load A has the strongest fast acting component, Load B has a moderate fast acting component, and Load C has no fast acting component at all.

    This is how our probability cuvres represent tha ability of a given load to impart a "shock" effect.


    Good explanation of a fundamental trade-off.

    There was a time when the failure of a bullet to expand was a legitimate concern. However, there are many loads available today using bullet designs at velocities where failure to expand is only a remote possibility.

    This is correct if everything else (mass, diameter, bullet type, reliability of expansion, penetration) is equal. Once you make a tradeoff to get more velocity, it gets a bit more complicated whether you gained more than you lost in the tradeoff.

    Good point.

    Weight used to be more important for penetration than it is today. Modern designs can penetrate very reliably in the moderate bullet weights, and even sometimes in the lighter bullet weights.

    Certainly, the best loads in these cartridges are relatively good performers. But load selection and bullet design are very important. The more poorly performing loads in these cartridges might not be as good as the best loads in 9mm. Also, the 41 Magnum and 45 Colt might be hampered somewhat by having very few of the best bullet designs available.

    I am no big fan of the 9mm, but I think it best to consider careful, quantitative research to determine the size of the effectiveness gap between the best 9mm loads and more "powerful" loads such as the .40 S&W and the .357 Sig. Once the size of this gap is quantified, then individual shooters can make their own decisions whether the added recoil, handgun bulk, and cost are worth the added effectiveness.

    The first rule of gunfighting is to bring a gun. The .380 ACP is a lot more effective than angry words. I have also seen the .380 ACP function well as an introductory gun that gives a person an opportunity to obtain training and a CHL and gain a comfort level carrying a gun. Once they have carried a .380 ACP for a while, they have a chance to consider what might actually happen if they need to shoot someone. This is often the birth of a desire to move up in power.

    One of the scientists on our team recently moved up from .380 ACP to .357 Sig, because our efforts to quantify stopping power made it clear how big the effectiveness gap really is.

    There are many cases where I would be happy for my students to move up to the .380 ACP because they come to CHL class with the intent of carrying a 22LR or .32 ACP.

    Michael Courtney
     
  9. Preacherman

    Preacherman Member

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    Michael, you make a good case for your analysis, but it's fatally and fundamentally flawed in its most basic premise.

    This is all very well - but it ignores the reality that your TARGET will be different in each shooting, whether or not your LOAD performs statistically better or worse than any other. I've been personally involved in well over (WELL over!) 100 shooting incidents, both military and civilian, over an 18-year period of warfare and civil unrest in another country, and as a citizen in this country since that time. I have never yet seen any opponent in a shooting match match another opponent in age, size, weight, sex, motivation, drug-enhanced imperviousness to pain, and so on. The fact that the loads you're measuring might perform the same is basically irrelevant if the targets won't perform the same!

    This is where the "scientific approach" to "stopping power" falls flat on its face. I fully agree with you that there's a place for scientific investigation, particularly of bullet and load performance: and I agree that consistent performance in ballistic gelatin and other test media is a good indication of how a bullet will perform in flesh. Unfortunately, none of these tests can be applied to how a given individual will react to being shot with that load, even if the bullet is placed in the same organ of the body every time, and performs at its best. Some will drop right there. Others will be on their feet for at least a few seconds, and be more or less incapacitated. Others will completely ignore the hit and continue shooting back at you, possibly to your permanent detriment. I absolutely do not agree that the behavior of an opponent can be "scientifically" predicted. Human nature ain't all that scientific, and human behavior has defied scientific expectations far too many times for me to reduce it to a probability line on a graph! For excellent illustrations, see the citations of Medal of Honor winners...

    The real world simply isn't the same as the laboratory. Whenever I find a scientist who thinks he can accurately, consistently and inerrantly predict the real-world outcome of something so inherently unstable and variable as a defensive shooting scenario, I start to worry about that scientist's safety.

    On this we fully agree. The times that I got shot were typically when I wasn't moving and/or taking cover (sometimes this just isn't possible under the particular circumstances involved). Most of the opponents who got shot were laboring under the same handicap.
     
  10. Michael Courtney

    Michael Courtney Member

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    We're not ignoring the reality of different individial targets, we are averaging over these differences.

    Different individuals each have different genetic predispositions to cancer. Environmental factors further complicate the issue. There is a very wide range of variation. Does this mean that a scientific study cannot be performed to determine the probability curve for contracting cancer after smoking brand X for a certain number of years?

    Suppose a scientific study compares the probability curves for contracting cancer after smoking Brand X for a certain number of years and smokng Brand Y for a certain number of years. In spite of all the complicating factors from the genetic and environmental variations in the specific cases, such a study can be done, and would constitute a valid scientific basis for concluding that Brand X creates a higher or lower cancer risk than Brand Y.

    These same kinds of studies are the ones that can conclude that exposure to sunlight increases cancer risk over time, or that certain foods can reduce the risk of certain cancers. In each case, there are broad variations in genetic and environmental factors, but sufficient numbers of data points can effectively average over these factors and understand how the variable of interest effects the outcome.

    There is no claim in this kind of research that the outcome can be predicted for a specific individual, but only that the percentage of outcomes can be predicted for a large number of individual events.

    In light of this, how is the definition of stopping power I have provided not relevant for the person in a large law enforcement agency who is choosing ammunition that will likely be used in hundreds or thousands of gunfights over the period of several years?

    We make choices every day to do things that only improve our safety in a probabilistic manner.

    We wear sunscreen.
    We try and quit smoking.
    We lose weight.
    We have our cholesterol checked.
    We buy a fire extinguisher.
    We check the batteries in our smoke detector.
    We investigate the safety record of a model of automobile before we buy it.
    We investigate the probabilistic failure rate of our method of contraception.
    We (females) get mammograms after a certain age.
    We (men) get prostate screenings after a certain age.
    We might even eat oat bran.

    Why then is it so strange to try and have a probabilistic understanding of bullet effectiveness to aid in ammo selection?

    Michael Courtney
     
  11. Preacherman

    Preacherman Member

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    <sigh>

    Again, Michael, with the greatest of respect, you have NOT defined "stopping power" in your study. You have attempted to define "bullet performance". Bullet performance is only one part of the equation: the other is the reaction of the target to that bullet performance, and that cannot be scientifically defined.

    "Probability theory" is just that - it deals with probabilities. Such probabilities don't often match up to the theory in real life. To take your example of a certain brand of cigarettes being more or less likely to cause lung cancer, there are innumerable cases of smokers dying young from cancer - and equally innumerable cases of smokers living to a ripe (if not necessarily healthy) old age. How to predict which one will get cancer, and which one won't?

    I agree that scientific research into bullet performance can help a police department, or a private citizen, make an informed choice of caliber, bullet, etc. in an attempt to have the best possible defensive equipment on hand. This is fair, valid, and appropriate material for research. However, the "real world" performance of that defensive equipment will not conform to laboratory expectations or predictions, because those results could not allow for the unpredictable factor of assailant behavior. They are an indication, but not necessarily a valid predictor.

    I've seen far too many cases where the results of a shootout were completely out of line with what any scientist or knowledgeable shooter would predict, based upon expectations of bullet performance. I've seen people whose heart/lung area was literally shredded by multiple bullet strikes remain functional (and shooting back) for 30-40 seconds, long after "theory" states that blood loss and oxygen deprivation should have put them down. Unfortunately, they hadn't read the theory, so they didn't behave that way. The autopsy results were graphic and gruesome, but even the pathologist couldn't explain why, with so much damage, they continued to function.
     
  12. middy

    middy Member

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    You can't, but you can calculate the probability. Statistics is not cut and dried.

    Basically what you're saying, Preacherman, is that the results of gunshots are so wildly unpredictable that we all might as well go moose hunting with .22lr.

    I disagree, there is a reason that I would rather use a .30-06 than a .22lr on a moose. That reason is that I am much more likely to get a one-shot kill because of the greater energy of the .30-06 round.

    Statistics most certainly can be applied to this problem to determine the relative "stopping power" of, for instance, a high-tech 9mm hollowpoint vs. .45acp ball. Statistics cannot guarantee a one-shot stop, just as you cannot guarantee you will die of lung cancer by smoking, but they can give you an idea of the likelihood of an expected outcome depending on the factors involved.

    With all due respect, I'm sure you could be a valuable resource for Dr. Courtney with your vast first-hand experience with these things, Preacherman, but science is science, and repeatable experiments conducted with valid scientific method over a large enough sample produce statistics that are quite usable in the real world, as I'm sure the QC guys at the company you bought your tires from would agree.
     
    Last edited: Dec 20, 2005
  13. Michael Courtney

    Michael Courtney Member

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    You say TO-MA-TO, I say to-MAH-to.

    If the definition is clear and empowers scientific quantification, whether or not we apply the label "bullet performance" or "stopping power" is only a matter of semantics.

    One term might communicate the essence better to the casual observer, but the careful reader who understands the details of the definition will not get hung up on the label once it is clearly defined.

    The range of reaction possibilities can be described, as can the probability of a specific target demonstrating a specific reaction possibility.

    You can't.

    But this does not mean that a particular individual does not increase his odds of living to a ripe old age by quitting smoking.

    Likewise, one can increase ones chances of surviving a gun fight with a better ammo choice.

    Probability theory correctly predicts that almost anyone who spends enough time and money gambling as a customer in a casino will come out on the losing end, and that the owners of the casino will come out on the winning end. The outcome of any specific bet is not predictable, but the eventual outcome of a large number of bets is predictable.

    I agree.

    The research also has important implications for training, shot placement, and furure bullet designs.

    Individual reactions cannot be predicted. But this does not preclude the possibility of predicting the probability distribution of a large number of individual reactions.

    Most cases fall near the middle of the probability distribution curve. But our definition of stopping power also encompasses the idea of a "worst case scenario" where the bullet fails to produce the expected result.

    Our definition of stopping power does not depend on a physiological understanding of what "should" happen given a certain wounding, but is only concerned with what does happen for a given load in a specified shot placement.

    Our definition of stopping power doesn't need a physiological explanation as to why these kinds of cases occur in order to quantify the fact that they do occur and to describe how often they occur. A worthy goal, is it not?

    Michael Courtney
     
  14. Camp David

    Camp David member

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    It might be well to update this handout with modern loads, particularly the upper range hot calibers... I refer here, Preacherman, to some of the newer calibers; i.e., .454 Cassul and .480 Ruger, as well as the fairly obvious .44 Magnum... Conversely, from the lower spectrum, I would love to see stooping power estimates for small caliber rounds, even rimfire loads; i.e., .22 and .22 mag...
     
  15. riverdog

    riverdog Member

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    I'm no expert, and

    I shouldn't even enter this thread, but I have to side with Preacherman on this whole stooping power thing. We can all agree that a CNS shot is a fight stopper, but it isn't very caliber/load dependent, it is very much placement dependent, assuming a projectile which can penetrate. Anything else requires either a blood pressure drop to force the individual to stop the fight, or what has been called a psychological stop.

    Blood pressure drop corresponds to the rate of blood loss and has as much or more to do with what was damaged than what caliber did it. A .45 ACP hit to the left shoulder may be a nasty wound, but if it doesn't cause massive bleeding, the fight can continue strong side only. OTOH a .22LR hit that clips the aorta will cause a rapid blood pressure drop. There's that shot placement thing.

    A psychological stop OTOH has more to do with mental attitude. Some guys will go down from a non-life threatening wound even though they could physically continue the fight; others will not go down until their blood pressure drops to critical levels. This stop is very dependent on the target audience -- physical condition, mental preparedness, regard for personal well being, et al. How do you quantify psychological stops by discussing calibers and loads? Apples and oranges.

    In a controlled test where all targets are shot with identical shot placement, and 20% are stopped at 2 seconds and 90% are stopped at 11 seconds, is the difference caliber related or psychological? How do you quantify a psychological stop?

    $.02
     
  16. Preacherman

    Preacherman Member

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    Michael, I'm not going to get into a numbers debate here (and yes, I do know something of statistics, having studied them at MBA level - not a mathematical genius, by any means, but I understand their use). I will simply repeat that you are not, repeat, NOT, defining "stopping power" by measuring bullet performance. A simple illustration will confirm this.

    The usual definition of "stopping power" (which is a very nebulous concept in itself, and not susceptible to scientific definition) is that, upon being struck, the victim immediately ceases all threatening and/or harmful behavior. Now, if a high-performance bullet strikes him, we can reasonably and legitimately expect it to do better than a low-performance bullet - but it still has to be placed in the right spot to do enough damage, and the victim has to react to being shot by stopping his aggression. If the bullet hits anywhere but the right spot, it probably won't stop him. If it hits the right spot, but he continues his aggression, then, by definition, the bullet has had no "stopping power" at all (at least, not in the important sense: if he stops 10 seconds later, that's great, but if he's killed you during those intervening 10 seconds, your interest is likely to be purely - and posthumously - academic!).

    I value any and all high-quality, rigorous analyses of bullet performance. They are of great value in helping with load selection. However, such analyses are not, and can never be, reliable indications of real-world "stopping power".
     
  17. mosttoyswins

    mosttoyswins Member

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    Myth...

    Don't get caught up in stopping power.

    Practice and shoot what you are good with.

    Just read the articles about people shot once with a .22 that dropped dead, and the people shot 10 times with a .45 and lived.

    I carry 9 rounds of 9mm, 5 rounds of .38sp. or 11 rounds of .40. To me they ALL have stopping power.
     
  18. Blackhawk 6

    Blackhawk 6 Member

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    Here is what I understand to be your premise, please correct me if I am wrong.

    1. Your proposed definition of stopping power is "the time interval required to achieve involuntary incapacitation in 90% of the cases where the target is hit with that load at the specified placement."

    2. You plan to determine the "stopping power" of a given load by measuring the time it takes to involuntarily incapacitate someone if they are hit in the "specified placement."

    3. By graphing these times you can compare one load against another.

    Based on that understanding I pose the following questions:

    1. How do you intend to measure the time interval?

    2. What is the siginficance of the "90%" and where is this percentage derived from?

    3. How do you account for those instances where an individual is struck in the "specified placement" and remains in the fight for an unbelievable amount of time? (See here for an example: Http://www.thehighroad.org/showthread.php?t=168247&highlight=NYPD)
     
  19. goalie

    goalie Member

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    "Stopping Power" is a funny concept. While I have nowhere near Preacherman's experience, I served enough time to know that a full-sized M16 doesn't have enough "stopping power" to satisfy me if I am in close quarters clearing a bunker or a room.

    Talking about it in regards to handguns just makes me chuckle because those guy you read about getting medals for fighting away with an E-tool after being shot 10 times, those guys are not all on our side. Brave, tough, motivated SOBs can be found on both sides in war (or on the streets), and acting like a formula has any relevance in the real world just seems like it's either a scam to sell some more ammo, or a way to get killed when you stop shooting your super-duper-wiz-bang ammo after one shot and the guy you shot doesn't stop fighting.

    Anyhow, good luck with your research. I hope that, if you ever get into a gunfight, it's only with statistically average opponents.
     
  20. Michael Courtney

    Michael Courtney Member

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    It is an unproven presupposition that all stops are either CNS hits, blood pressure drop, or voluntary. We sought a definition that would allow for stopping power to be quantified without resorting to this unproven presupposition.

    In other words, we wanted to let careful experiments and observations determine whether there is an incapacitation mechanism that works faster than blood pressure drop without a direct hit to the CNS.


    Quantifying voluntary stops are challenging, but the voluntary stop can be largely removed from the problem by performing live animal experiments on species that do not exhibit a voluntary (or psychological) stop. If one can demonstrate incapacitation in live animal experiments more rapidly than required for the blood pressure drop, and without a hit to the CNS, then one has significant experimental support for another mechanism that acts more quickly than blood loss.

    Michael Courtney
     
  21. Michael Courtney

    Michael Courtney Member

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    This is only one component of the definition. The full definition is the entire probability curve. If one desires to summarize stopping power in a few numbers, one might use the time to achieve incapacitation in 90% of the cases, the time to achieve incapacitation in 20% of the cases, and the average incapacitation time.


    Yes, that is the idea.

    Yes.

    In live animal experiments, measuring the time interval is easy.

    For cases where the target species is human, we are developping new techniques in forensic science to allow for analysis of audio/video records of shooting events to determine which shots are hits (and where they hit) and which shots are misses. Given the increasing number of shooting events captured with surveillance equipment, accurate time reconstructions should be possible for significant numbers of shooting events.

    As I wrote above, you really need the whole curve for a full definition, but we believe that three bits of information would be a good summary. 90% is not particularly significant. You just need a sense of the low end (20%), a sense of the middle (the average), and a sense of the high end (90%). One could choose 95% or 99% if they prefered.

    They will appear at the appropriate location in the probability distribution, depending on how often they occur. If they occur more than 10% of the time, they will increase t(90%), and regardless of where they occur in the distribution, they will affect the average incapacition time.

    Michael Courtney
     
  22. GoBrush

    GoBrush Member

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    have not read this post just yet printing it out now. BUT

    I think when talking about stopping power it is important to remember the advancements over the past several years on defensive ammo. With modern ammo such as Hydra Shok's and my favorite Gold Dot all calibers are not created equal but it has sure closed the gap between 9mm, 38spl all the way to full power 45's. I cut my teeth on full power 357's and 45's and LOVE THEM but in my old age and these advancements realize that control is just as important when considering what to buy.

    By the way I still shoot the big boys and hold my own with any one just getting smarter with age I guess.

    Stopping power is really not as important as how much you practice and how confident you are with your abilities.:)
     
  23. Sam

    Sam Member

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    Preacherman got this one exactly right:

    Given there is no way we can ensure exactly identical shot placement, level of excitation of the target individual, size of the target individual and all the other variables, I consider it pretty much an exercise in futility to make an attempt to quantify such a thing as "stopping power".
    Make nice converse sitting around the woodstove but the only thing that counts is good placement, preferebly a CNS hit.
    Unless you can afford a bearer to carry your M1 around 24/7 you are not going to be adequatly armed when the time comes. Sucks doesn't it:evil:

    Sam
     
  24. JohnKSa

    JohnKSa Member

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    There IS such a thing as stopping power. It's just not currently possible to RELIABLY predict the stopping power of a given gun/ammo combination.

    I don't know if that will change, but I certainly hope that as time passes, science will help us understand the problem better.

    Right now, there's a marked disconnect between the simple physics and the noted effects. That is, given the easily measurable and calculable parameters of a projectile, it hasn't been possible to consistently associate these parameters with the effectiveness of the projectile unless there is a gross variation in the parameters. The answer isn't that the physics is wrong, it is that not enough of the problem is well understood and defined. I.e. there are more parameters that must be measured and understood before the problem will become tractable.

    Part of this is that the shot placement issues affect the problem so profoundly. That will have to be taken out of the equation initially and I can't see any way to do that without carefully controlled experiments involving live animals.
     
  25. cz75bdneos22

    cz75bdneos22 Member

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    why don't we do our own investigation?
    let's sign up some volunteers random(sample)...agree on the testing methodology...and draw names to see what caliber you will be testing with...and publish the results in the name of research...:D see below ...;)
     
    Last edited: Dec 21, 2005
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