Webley, the cavitation is almost identical in displacement between common SD rounds. We've all seen the picture of the gel tests comparing the 9mm up to the .45 (including the 10mm as a joke sometimes).
Yes, you're right. There really isn't all that much difference between the popular service calibers (which I've said in other threads before and is one of the reasons that I think the 9mm vs. .45 debates are stupid). However, I'm not necessarily talking about just the popular service calibers. If you compare one of the service calibers like say .40 S&W to a small caliber like .32 ACP, you'll get very different types of performance. Likewise, if you compare that same service caliber to something like a .44 Magnum you'll get different performance. Consider the following:
http://www.brassfetcher.com/Speer240grainJHP.html
http://www.brassfetcher.com/180gr%20Winchester%20Ranger%20JHP.html
http://www.brassfetcher.com/9x19mm147grGoldenSaber.html
http://www.brassfetcher.com/230%20grain%20+P%20Winchester%20Ranger%20JHP.html
In particular, notice this from the .44 Magnum test:
"Temporary cavitation from this round broke the wooden board that the block was sitting on, into two pieces lengthwise."
Because the .44 Magnum was the only handgun bullet that was able to do that, it is only logical to conclude that the .44 Magnum produced a significantly larger temporary cavity than the 9mm, .40 S&W, or .45 ACP.
Beyond that, it doesn't do all that much to aid in incapacitation itself, especially when considering poor placement, until you get into very fast-moving rounds, like rifle rounds, where it can cause much greater damage. Of course, it does add damage regardless, as I've said previously, but not a whole lot. Much of the stronger tissues in the body will not give as easily, and much of it will not be damaged beyond minimally. This is assuming the round passes close by the organ, not into it. When the round strikes the organ, the cavitation is the very least of the problem. Cavitation effects from a .22 LR pistol and a .44 Mag pistol will differ...no question. Assuming you made a clean shot to a vital area, the placement of that bullet is going to be the stopping factor, not the side-effect (cavitation). Assuming you shoot a non-vital area, that cavitation difference itself is not enough to shut the body down any faster. It comes down to shot placement in these cases, once again.
It depends on what the bullet hits and the circumstances in which it happens. Take the example you mentioned earlier of the man that was shot in the head with a .40 S&W. You said that he lost his sight but survived which leads me to believe that either a) the bullet did not actually hit the brain but rather the optic nerves or b) hit an area of the brain that is involved in sight such as the occipital lobe. If we assume that b is what happened and that the bullet did indeed impact the brain, then it is relatively safe to say that the bullet did not cause a great deal of temporary cavitation. If it had, brain tissue would have been compressed to the point that it would've likely been forced down through the foramen magnum which in turn would have likely caused hemorrhage of the brainstem which would cause instantaneous incapacitation and death.
Also, with regards to your example of a shot through the heart. The heart is a rather resilient organ and penetrating trauma to it is not guaranteed to be instantaneously incapacitating. While it is true that cardiac muscle is tough and elastic, the tricuspid, bicuspid, semilunar, and mitral valves as well as the chordae tendineae are not as I mentioned earlier.
Also, a smaller diameter projectile that creates a larger temporary cavity such as a .357 Magnum is more likely to cause a cardiac tamponade than a larger diameter projectile that creates a smaller temporary cavity like a .45 ACP. The reason for this is that the pericardium can more easily seal the smaller diameter hole, but the larger temporary cavity is more likely to rupture the capillaries on the surface of the heart. A cardiac tamponade is, by definition, a condition in which the pericardium becomes filled with fluid that cannot escape and therefore creates pressure on the heart leading to ineffective pumping, shock, and if untreated death.
In your examples, you mention the cavitation effect when striking the organ. The key part of your discussion is a properly-placed shot (since it actually strikes the organ, causing damage/destruction). Cavitation may or may not have the effects you listed (impossible to say with certainty), but even so, it will be present with all rounds fired. Between a 9mm and a .40, what difference do you really think you will see?
I'm referring to the effects of temporary cavitation in a shot that penetrates a vital organ. Most organs can be displaced enough from the outside that temporary cavitation from a near miss will not cause significant injury. I'm not talking about injury from bullets that don't hit a vital structure but rather the extent of damage from bullets that do.
Also, I don't think that you will see that much difference between a shot from a .40 S&W and one from a 9mm. However, I do think that you may see a significant difference between a shot from a 9mm and a .44 Magnum or between a shot from a .32 ACP and a .40 S&W.
A big thing is variability in the body. Someone in the world may fall to side effects of a bullet, as I'm sure some have. But, that is the exception, rather than the rule.
Is bigger better? Sure; you get more margin of error. Is faster better? Sure. Cavitation effect is a function of velocity. Is it enough difference between the commonly-used self-defense rounds to give a clear advantage? No. Is the difference enough between a .22 LR and a .454 Casull? I'm sure it is.
That's the brunt of the point I've been trying to make all along. Temporary cavitation is a poor substitute for proper placement and adequate penetration. As I'm sure nearly everyone would agree, a good shot with a .22 beats a bad shot with a .44 Magnum. However, I maintain that temporary cavity is not completely insignificant and that it can, under the right circumstances, have a significant effect in wounding. For this reason, I cannot understand why someone would choose a cartridge or loading with less energy over one with more unless a factor such as penetration, shootability (and therefore accuracy), or practicality of platform would have to be sacrificed in order to do so.
Quote:
So if a solid hit to a vital organ is all that is needed, why are some cartridges decidedly better than others?
Decidedly by whom? A bunch of gun writers and shooting instructors? It is NOT 'decidedly so' by anyone who has actually had to treat these wounds. The thing is they all are equal as stoppers. None better, none worse...it is decided by shot placement and not caliber, when speaking of defensive handgun rounds.
Again, you assume that I'm limiting the discussion to common service calibers. I have yet to see any credible expert who claims that a .22 Long Rifle is equally effective to a 9mm. Yes, some cartridges are decidedly better than others, its just that the comparisons aren't limited to the cartridges you think they are.
The only reason many feel it is possible that these rounds can actually be ranked is because they read books on the subject, written by people who are not qualified to do such ranking.
They read, but did not fully understand, books that were written by people who did not fully understand their findings. The problem is that people want to base their decisions on part of the information contained in the M&S studies, FBI reports, Thompson-LaGarde tests, or just about any other work on handgun wounding without understanding how and why the results were what they were.
To use the car analogy, it's like when people compare an E30 BMW M3 to an E30 325iS. At face value, the M3 would seem to be the superior car because is generates more horsepower (192 vs. 168) and has a better 0-60 time with a higher top end. What many people don't understand is that the M3 generates it's peak horsepower at much higher RPM's than the 325iS does and that the midrange acceleration of the 325iS is actually better due to its flatter power curve. While it is true that the M3 is a better race car, the 325iS is a better road car but someone who simply looks at the specs without understanding them doesn't know it.
That, and the "tall tales" told over the years giving some rounds legendary status for all the wrong reasons. Of course, we didn't know any better back then. We didn't use aids, such as CT/MRI, to image soft tissue damage, wound tracts, etc.
And some of the true "junk science" of yesteryear like the Thompson-LaGarde tests of 1904 which can't really tell of much of anything other than the fact that neither Thompson nor LaGarde knew how to run any sort of scientific experiment.
