Here is an interesting, recent, true story that addresses this a little.
Dr. Fang was a well known, serious competitive shooter in the San Francisco area. He was as good, or better, of a shot than any of us, and he could do it all against a clock against multiple targets.
Two RBG's (really bad guys) with guns busted down his front door and started pistol whipping his wife as well as the nanny. Dr. Fang answered immediatly by bursting out of the bedroom with his .38 Revolver. Dr. Fang ran into battle to defend his family furiously.
Dr. Fang emptied his revolver into both targets, killing one on the spot and critically wounding the other. While he was firing, and hitting his targets, Dr. Fang was prevailing and overwhelming his enemies....but he ran out of ammo.
The problem being that really-bad-guys don't die instantly on the spot; they live and can wreak havok for at least a few seconds, even after being shot numerous times.
So, as Dr. Fang ran away to reload, and the bad guys saw that he was no longer a threat, they fired on him. He was shot in the back and killed.
Then, the bad guys fell down.
There are many morals to the story, but one of them is that it takes more than several rounds and good shooting to handle two really-bad-guys.
(I personally believe that gun control killed Dr. Fang: He should have had a hi-capacity semi-auto, but they are effectively illegal in California.)
So, no matter what anyone says while posturing in machismo, I do NOT feel that 7 rounds is enough for today's circumstances and the saying is not true that "if you can't do it in 6 or 7 rounds then blah blah blah (fill in macho statement here)".
Dr. Fang was an excellent competitive shooter. He hit is targets when it mattered most, killing one on the spot and critically wounding the other. He did his part. But, sometimes you DO need more than several rounds, no matter how good you are.
(Sarcasm follows)
But, I am sure that the bad guys would have fallen down instantly at one good hit with a .45 and he only would have needed two bullets (one for each, instant kills). Or better yet, they would have seen the muzzle and ran out of the house screaming in fear of that big bullet. Dr. Fang would be alive today if he had had his 1911 .45. (sarcasm off)
Lastly, we can pontificate all we want about how Dr Fang should have used a shotgun yadda yadda yadda. But, reality is that he used what he had on him in an instant's notice, to defend his loved ones.
I do feel that the 12 rounds of .40 would be preferable for me, as long as it was in a platform that I could shoot extremely well.
But, it is highly arguable, and been discussed many times, whether the .40 is really anything more than a +P+ 9mm. So, make your own choice. There might be a slight chance of more hitting power with the .40, but it is really a toss up.
I can't really decide what I would want, now that I think more about it. I can engage targets damn fast with a 9mm, and now that I think about it, I would rather plug 5 rounds into someone's chest with a 9mm in one second, than to have a slightly more powerful gun and only hit with half of that in the same amount of time.
No matter how good I get, and how much I practice, I still shoot faster, more accuratly, (under stress and severe circumstances), with the lighter recoiling 9mm. I suspect that most other people out there are the same, even if they won't admit it.
Ps- there are very many accomplished serious shooters out there that weigh all the factors and decide that the 9mm is the best choice. We really need to put away this stupid idea that anyone who uses a 9mm is an ignorant beginner. There are benefits to each cartridge, and some very hardcore shooters weigh them out and decide the 9mm is the better choice.
[This message has been edited by Red Bull (edited July 12, 2000).]