An EXTREMELY informative article by Chuck Hawks about handgun stopping power
http://www.chuckhawks.com/beginners_stopping_power.htm
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Much of what one reads about the subject of handgun stopping power is a mixture of truth, half-truth, untruth, rumor and legend. A good place for inquiring minds to start would be to read the books by Ed Sanow and Evan Marshall, which are the most important works on the subject at the present time. They did the research, visited the morgues, talked to the shooting victims and police, and in the end collected the validated data from actual shootings that demonstrates what has worked in the real world. Their findings can correct a lot of popular misconceptions for those who are willing to learn.
When discussing terminal ballistics what seems "reasonable" on the face of it often turns out not to be, sometimes for fairly complex reasons. One example would be the alleged superiority of the semi-wadcutter (SWC or "Keith style") bullet form. General Julian Hatcher, who invented the widely quoted (and copied) theory of Relative Stopping Power, and those who followed his lead theorized that such a bullet should be 25% more effective than the traditional Round Nose (RN) bullet. And, in fact, the SWC style bullet does look somehow deadlier than a RN bullet. Its sharp shouldered, truncated cone configuration was alleged to "chop" a chunk out of tissue and blood vessels as it passed through, rather than press them aside as it was alleged a RN bullet would do. This seemed to make sense to me, and for years I shot SWC style bullets. But when Sanow and Marshall evaluated over 100 actual shootings with 158 grain .38 Special lead SWC bullets, there proved to be no significant difference in stopping power compared to 158 grain .38 Special lead RN bullets at the same velocity. Clearly, the Hatcher theory has some flaws, no matter how reasonable it may seem.
The stopping power of any handgun bullet turns out to be a function of its ability to disrupt vital bodily functions, not the diameter or weight or initial shape of the bullet that strikes the victim.
For example, the difference in the size of the entrance hole made by a .451" bullet compared to that made by a .355" bullet in an elastic (semi-self sealing) material like skin turns out to be largely irrelevant to stopping power. The idea (which I have heard expressed) that a bigger bullet makes a bigger hole to "bleed out" a man or an animal is faintly ridiculous.
The principle method of both stopping and killing with any firearm, whether rifle or pistol or shotgun, is the disruption of vital bodily functions. Fatally damage any animal's heart, liver, lungs, or central nervous system (including Homo sapiens) and it is not going to live long enough to bleed out. Fail to put your bullet in a vital spot and you are very likely to have a problem with a man or an animal. That is not to say that some bullet placements might not eventually cause death by loss of blood, or infection, or some other mechanism, but that is never the goal of any hunter OR gunfighter who wants an immediate one shot stop.
Readers who have done some deer hunting have probably observed that often the entrance wound from a modern expanding rifle bullet (like a 100 grain .243, 130 grain .270, or 150 grain .308) seems minimal, with almost no external blood loss at all. In addition, there may be no exit wound--the bullet is often found just under the hide on the off side. But if the shot was true the deer's lungs probably look like they went through a blender, and the animal was down in seconds. That is an illustration of nearly perfect stopping power and it has little or nothing to do with the relatively small caliber of the bullet involved.
Modern big bore advocates, following in the footsteps of Jeff Cooper (who I respect greatly and regard as a fine and very persuasive writer), will claim that the example cited in the paragraph above and witnessed by countless tens of thousands of deer hunters does not apply at typical handgun bullet impact velocities. They argue that below some magic impact velocity (usually about 2000 fps) the temporary stretch cavity that contributes so much to the lethality of rifle bullets like those in the example above ceases to exist. These writers continue to ignore any facts contrary to their preconceptions. (As an aside, it is interesting that big bore rifle fans use a similar argument, but for them the magic velocity is typically about 2400 fps.)
Unfortunately, they are simply wrong about pistol and rifle terminal ballistics being fundamentally different, which can and has proven by controlled testing and high speed photography. In fact, they are fundamentally similar. Both depend on disrupting the function of vital organs, and bullets that reach such organs and expand quickly and violently, thus destroying a lot of tissue, are the best way to accomplish this, whether fired from a short barrel or a long one.
How could the terminal ballistics of pistols and rifles be so different, since today we have pistols chambered for rifle cartridges and rifles chambered for pistol cartridges?
In general, rifles have an advantage in kinetic energy, and this gives them an advantage in the amount of potential damage they can cause. (Of course, most of the big bore boys don't believe that kinetic energy matters, either, but that is their problem.)
But in terms of the mechanisms of wound dynamics, rifle bullets and pistol bullets are both bullets, and function in pretty much the same way. The stopping power of pistol loads and the killing power of rifle loads are both based on a combination of the temporary stretch cavity and the permanent crush cavity produced by the bullet as it traverses the target. Any theory that ignores either of these factors will give erroneous results. Ignore the temporary stretch cavity and your results will favor big caliber bullets. Ignore the crush cavity and your results will favor high velocity, nearly explosive bullets. Both results will be incorrect.
For at least 40 years I have been reading claims by various "authorities" that bullets cannot be made to expand reliably at typical handgun velocities. This is just plain not true. I discovered that in the middle 1960's by shooting game with .357 Magnum JHP expanding bullets, and it certainly isn't true now. These opinions usually trace their origin to ancient theories and flawed experiments, particularly the Thompson-LaGard study conducted around the turn of the (20th) Century and General Julian Hatcher's aforementioned Theory of Relative Stopping Power.
When applied to contemporary handgun cartridges, theories based on Hatcher (which include Cooper's and Taylor's "Short Forms") have a statistical correlation to reality of only .64. In other words, they are meaningless. A vocal minority of gun writers and their disciples (again mostly big bore pistol fans) have come to accept this bunk as gospel, but it is really in the same category as urban legends. These "authorities" have been repeating this misinformation for as long as I can remember--but that does not make them right.
It is instructive to read the actual results of the Thompson-LaGard cattle shooting experiments, which I have done. I urge my readers to do the same. It would be hard to imagine a less appropriate or more poorly controlled study. Despite the significance ascribed to it to this day by the ignorant and willfully blind, it proved absolutely nothing about the lethality or stopping power (on humans) of the handgun cartridges and loads tested. And it is even less relevant (if possible) to modern handgun ammunition, since no expanding bullets were tested.
All that the Thompson-LaGard experiment really proved is that none of the handgun loads tested were effective at killing cattle. Most of the bovines those early experimenters shot had to be put down with a sledge hammer! The conclusion that the .45 caliber pistol was superior was forgone from the outset due to the bias of the testers, and it became their official conclusion despite a startling lack of data to support it. Interestingly, the only steer put down quickly with one shot was killed by a round from the high velocity 7.65mm (.30 caliber) Luger pistol!
Well designed bullets (which includes most of the JHP pistol bullets now on the market) expand very reliably at their intended impact velocity. How do you imagine the 115 grain JHP 9x19 +P load, 125 grain JHP .357 load, 155 grain JHP .40 S&W load, and 230 grain JHP .45 ACP loads earned those outstanding 90%+ one shot stop records in the real world? In a sentence: due to the consistent performance of their JHP bullets.
The famous 125 grain .357 JHP bullet, the most effective one shot stopper of all handgun loads, penetrates 13.25" in ordinance gelatin and produces a football shaped stretch cavity. This is how the very best bullets perform. And bullet performance has a great effect on stopping power.
For example, the .40 S&W has higher one shot stop percentages in the real world than the 10mm Auto. Yet both use exactly the same caliber bullets, and the 10mm Lite load has exactly the same velocity as the .40 S&W. What gives?
The difference is a function of the terminal performance of the bullets involved. The FBI adopted the 10mm Lite load and became the main driving force behind 10mm load development. The FBI protocol calls for more penetration, and therefore less expansion, than is desirable to maximize stopping power in most shooting situations. They are more concerned about shooting through car doors, barricades, and so forth than putting criminals down with one shot in the typical frontal shooting situation that homeowners and civilians are most likely to face. The FBI essentially wanted ammunition designed for extended gun battles with perps hiding behind cover, and that is what they got. But as a result most 10mm ammo has less actual stopping power than the lighter, faster expanding bullets used in the best .40 S&W loads.
I wrote this article, not as a diatribe against big bore handguns (indeed, some of them--using JHP bullets--are near the top of the stopping power list), but because I have grown weary of hearing and reading the same old misinformation endlessly repeated. My opinion is no better than anyone else's unless it correlates with reality. Read the actual studies, not what others say about the studies, and decide for yourself. For those concerned with the problem, handgun stopping power is too important a subject to be left to urban legend.
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And this about stopping power in general
http://www.chuckhawks.com/rifle_killing_power.htm
An excerpt
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Linear momentum
Momentum is calculated differently from energy in that it is the product of mass and velocity--not the square of velocity. This slants the result in favor of heavy bullets, and makes momentum the darling of the big bore crowd. Momentum is what tends to keep a mass in motion moving, in accordance with one of Newton's physical laws. It is unclear how (or if) this relates to killing power.
Momentum is not widely referred to in the world of ballistics (terminal or otherwise). The term "momentum" is not even included in the Glossary of Terms in the back of the Hodgdon, Hornady, Lyman, Nosler, or Speer reloading manuals that happen to be piled on my desk as I write these words. (I checked!) I am inclined to conclude that momentum is a sort of red herring, favored by gun writers from the big bore school because it gives credibility to their existing prejudices in favor of big bore rifles and heavy bullets.
The term "pounds feet" invented, I believe, by Elmer Keith, is another favorite comparative tool of the big bore school of gun writers. Pounds feet is merely momentum divided by 7000 (the number of grains in a pound). The comparative result is the same as an ordinary calculation of momentum, but using the term pounds feet gives the result a sort of pseudo scientific ring, as the lay reader may easily confuse "pounds feet" with the legitimate scientific measurement "foot pounds."
As we have already seen, large diameter bullets tend to create a wide wound channel, and bullets that are heavy for their caliber have good sectional density and tend to create deep wound channels other factors being equal. These are clear advantages of heavy, large bore bullets from the standpoint of killing power. However, I doubt that calculating bullet momentum per se contributes anything to our understanding of the subject. Ditto for pounds feet.
Another of Sir Isaac Newton's physical laws states that for every action there is an equal and opposite reaction, calculated in terms of momentum. This would imply that, in terms of momentum, the recoiling rifle has more killing power than the bullet it fires, since its momentum is in fact the same as the total ejecta from the barrel (the bullet plus the powder gasses). It is true that big bore rifles kick like the devil, but I doubt that even the most fervent true believer wishes to defend momentum as an indication of killing power in that light, for if it were true they should all be dead.
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