Oh boy. Well, at least you didn't start a "9mm vs .45acp" Holy War.
Here's my take. (Feel free to ignore it.) Given an intelligent choice of modern JHP bullet shot from a reliable firearm, bearing in mind the fact that a pistol is an extremely poor choice to stop an attacker--there isn't really any difference between them at all.
Seriously, there isn't.
I'm not arguing that a .40s&w isn't a larger bullet, that may (or may not, depending on your load choice) have more power/momentum/energy/whatever calculation you like----however, in terms of terminal performance for citizens carrying for self-defense,
there really isn't any difference. (I'm going to ignore barrier penetration/lack thereof discussions for this, since most citizen self-defense shootings don't include those issues.)
So---what do you shoot better?
What will you practice with consistently? (What can you
afford to practice with consistently?) What can you carry consistently? (What
will you carry consistently?)
Most citizen shootings end in either the bad guy running away without a shot being fired, or a "psychological stop," meaning that the bad guy isn't actually physically incapacitated, but instead stops because
mentally they have had enough. As such, technically speaking, a .22 from a revolver can actually work quite well in a majority of such situations. (Interestingly enough, lots of "armed citizen" stories have .22s in them.)
That isn't to say that I think people should carry .22s. (Though it is better than a pointy stick.) I personally don't like the idea of carrying anything less than a 9mm (no, I don't like .380s or .32s, and the new Bond movie annoys me greatly) because with a 9mm it is certainly possible (though not easy) to achieve a
physiological stop. With less than 9mm it is still possible, but much more difficult to do---and MUCH more difficult to do
quickly.
With that being said, ANY handgun isn't very good at achieving a quick physiological stop. And the differences between said stop with a 9mm, .40s&w, and a .45acp is----minimal.
With every single one, it is about shot placement. With good shot placement, all three work just about the same. And if you don't have appropriate shot placement, then yet again---all three work about the same (meaning: not very well).
A good discussion of this resides at:
http://ammo.ar15.com/project/Self_Defense_Ammo_FAQ/index.htmNote: I don't always agree with DocGKR, nor do I always agree with Fackler. (There are some research issues I think they gloss over here and there.) That being said, I believe that the information presented in this link is pretty much spot-on with regard to:
1) equality between calibers,
2) choice of high-quality JHP,
3) the list of "best-choice" JHPs given, and
4) how most things that people worry about really don't make any difference.
My thoughts regarding ammo choice is that lots of LEOs carry Ranger-T, Federal HST, and Gold Dot ammunition. You can get those in .40s&w or 9mm---and they really do work about the same across all three versions of JHP and across the two calibers.
So---for YOUR choice: which gun will you practice with more and carry more, and most importantly, which gun gives you the best results for fast precise shot placement?
My personal choice is a basic G17: 9mm glock, 17+1 capacity. (Or a G19, which is my summer gun, with a 15+1 capacity.) I could use a G22 instead (same gun, same frame, 40s&w, couple less rounds), but my followup shots aren't
quite as fast (which is very minor, because the difference is tiny) and it is a lot more expensive to practice with and shoot (which is major, because practicing hitting exactly what you need is far more important than any almost-nonexistent difference in performance).
Which one will you get good with? Go with whatever that one is. And if you don't reload, 9mm is going to be a LOT cheaper than the other choice. (Even if you reload, 9mm will still be cheaper.)
By the way: Yes, 40 recoils more. But that really shouldn't be a big deal unless 1) you are attempting to shoot it out of a pocket pistol, or 2) you have incredibly tiny hands. My wife loves to shoot her .40s. (Significantly more than she loves to shoot her 9mms.)
