Jason K wrote:OK.....so, if FMJ will do the job in an emergency situation, why won't it do the job any other time? Why buy high-zoot JHP SD ammo at all? buy
Two reasons: efficiency, and the risks of over-penetration.
FMJs incapacitate or kill primarily by blood loss, unless they hit a vital enough target to instantly turn off the attacker's lights. Shot placement may be king, but in a dynamic situation with an adrenaline dump happening, target accuracy goes out the window, to be replaced with "combat accuracy"......which is why we talk about COM so much. In a live shooting situation, you can't absolutely depend on hitting your attacker's "off-button". Training helps, but that's all it does....help. It's not a guarantee. So as a practical matter, stopping becomes more a matter of causing lots of tissue damage and pain rather than hitting the light switch. FMJs are also more likely to pass right through the body, and that is dangerous to anyone down range from the target whom you would rather not shoot. In a
perfect world, there
isn't anybody down range from the target; but we know that this is not necessarily true in the
real world, even if we can't see them, which is why outdoor shooting ranges are back stopped by earthen berms. If it's indoors, what about innocents on the other side of the wall?
JHPs go a very long way to avoiding over-penetration issues. Also, by virtue of their expanded diameter, they
do cause some slight increase in tissue damage and wound channel bleeding....although it is restricted to bleeding out the entrance wound or into the abdominal or chest cavities. Bowel penetrations will also bleed into the bowel tract. They are also more likely to drag foreign debris like clothing fibers etc. into the wound track. They produce a larger temporary stretch cavity. This doesn't actually blow organs apart, but the stretching does cause micro-tearing of the stretched tissues, which leads to greater, more rapid blood loss, some kinds of tissue do not handle bullet shock well at all, particularly heavily vascularized tissues like the liver, which is very frangible and ruptures easily. You can bleed to death fairly quickly from getting hit in the liver. Other organs, including surprisingly the heart itself, will handle a gunshot wound better than the liver will.
For example: If a 9mm FMJ hits the heart, it has a very good chance of passing right through. It will
poke a neat hole in the pericardium on entrance and exit, and the holes in the pericardium will seal up, and the heart (being just a muscle, after all) will keep right on pumping with no blood loss into the chest cavity.
EVENTUALLY, the person will develop a pericardial tamponade and it will
eventually stop his heart and kill him, but not before he has had time to kill you and all of your family, AND make it to the hospital in his own car. Hit the same person in the same place with a modern 9mm JHP SD bullet, and those sharp petals on the expanded bullet will
tear a hole in both sides of the pericardium; the pericardium will not seal up, and the person will exsanguinate fairly quickly into his chest cavity. He will begin to feel the onset of loss of blood pressure fairly rapidly, and he will be more likely to be rapidly incapacitated.
All of the above applies regardless of what structures were hit by the bullet. Perhaps the only advantage of an FMJ over a JHP in a SD shooting is the FMJ's superior ability to break bones......but bones are an unreliable target (since you can't actually SEE them,they aren't always where you imagined them to be), and even FMJs can be deflected by bones instead of breaking them.
Since the whole point of shooting someone in self-defense isn't punishment, but rather to stop the attack, it simply makes more sense to use the bullet that will be more efficient in that regard, while reducing the risks to other people whom you might not intend to shoot. That would be the JHP.
My dad shot a Japanese soldier on Iwo Jima in the "stomach" with an FMJ from his 1911 at very close range. When I asked him how the Japanese soldier reacted to being shot, my dad said "he sat down rather abruptly" and didn't move anymore after that. It was after midnight and there was no obviously visible bleeding. Dad had no idea if he had actually killed the man outright or if he was just laying there hoping they would go away. The enemy soldier had stumbled into their position under dark and was surrounded by 7 very frightened and irritated marines in varying states of exhaustion and injury, any one of whom would have probably gladly finished the job if he had moved an inch. There was no profit in firing additional rounds at him as they were trying to get back to American lines without being discovered by anymore Japanese. All I know is that there was no
obvious sign that my dad's single 230 grain FMJ had done any damage to him, other than after my dad fired, the man slumped to the ground and leaned back against a hummock they were all hiding behind.
I would use FMJ in a pinch, and I've been gradually acquiring a stockpile of it for if/when "the pinch" comes, but since the demands of concealed carry place limits on what I can reasonably carry on my person, I'd rather depend on SD ammo for carry use because it is more of a sure thing than FMJ. If my carry weapon were an AR15, I wouldn't give it as much thought........although I do keep 55 grain soft points on hand for home defense use.
There it is, right answer! Give Cali a cigar....or something. 
