Originally Posted by Dutch
Also way too soft on punch (I know this from experience, after shooting a F'er in the shoulder with a 9mm that he shrugged off like it was nothing. I started carrying my 44 Mag S&W, no more problems (Desert Storm I). I'd go with the Glock 10mm (40 cal, and what I'm using now), or a 45 semi (still hard to beat, but rounds cost more). If you hit 'em, you'd like to know they are out of the fight ( ie shoulder shot = no arm). You cannot be sure of that with a nine. The 10mm is a great compromise between the muzzel velocity of a 9mm, and the punch of a .45.
If it was Desert Storm, I'm assuming you were military (also from your avatar) vs. a civilian contractor and therefore you were using FMJ with the 9mm (thanks for your service to the country, by the way). If using quality, newly designed (last decade or so) self defense/police duty (really no difference) ammo, the actual results from any of the common duty pistol calibers is the same -- both in gel tests and OIS (officer involved shooting) reports.
There has been a great deal of science that has gone into ammo development in recent years, and in large part the difference in calibers is marginal. That's why a lot of departments/agencies around the country that had moved to .45s or .40s in the '90s and '00s, are now choosing to move back to 9mms, because the effectiveness is similar, the ammo is cheaper, their officers should better qualifying scores with the 9mm (which means they will shoot better when using them for real), and the gun failure rates are lower.
The best place on the net for one stop shopping to learn about the terminal ballistics of modern ammo: http://www.m4carbine.net/forumdisplay.php?f=91