Gentlemen,
I mine as well join the fray...I've carried a gun literally every day for the past 18+ years whilst on the job, and off. And I've had occassion to see a few people who have been actually shot. So I have some opinions.
We all get caught up in the caliber debate...waxing poetic about the virtues of this caliber, and damning another, when, just as in hunting big game, bullet construction and shot placement are the most critical issues. The last three oxygen impaired via gun play individuals I've seen got that way courtesy of the lowly 22 rimfire, the anemic .25 ACP, and the much maligned 9mm. The common denominator in all three of these incidents besides "woefully underpowered" rounds, was excellent shot placement. The above trio ceased to exist most ricky tick despite the underpowered status of the calibers used. So...WHATEVER you choose to tote, pick a good bullet and be good with with the gun...real good.
Revolver vs Auto? They both have advantages and disadvantages, so pick the one you are comfortable with and can shoot. I can tell you, I've NEVER had a revolver not go bang, or malfunction. All my auto's, with the exception of a Beretta 92FS 9MM, have had malfunctions. I could not make that gun jam...despite intentionally neglecting cleaning, lube, etc. I eventually got bored trying to make it malfunction and cleaned it. Phenomenal gun...and I sold it...because I'm an idiot. The DA/SA guns (Beretta 92, Sig 226, etc), or whateverthehell Al called them, while probably not ideal, can be shot quickly and accurately...but you have to train to do it. I carry both autos and revolvers...a Glock 21 .45 ACP on duty, a H&K P7M8 9MM in my current plainclothes assignment, and a S&W 340SC .357 Mangleum off duty. I carry the Glock because I'm not worried about concealing it, it makes a big hole, and I can shoot it. The H&K because it's flat, easy to conceal, a great gun, and I can shoot it. And the Smith because it's REAL light, easy to conceal, and I can shoot it. However, I don't carry .357's in it...38+P's for me, thank you. I shot one cylinder full (5) of .357's in it and it was one of the singular most unpleasant gun experiences in my life. Mind you, I have a Freedom Arms 454 that I love to shoot, so I'm not exactly recoil shy, but that little gun was brutal. It is manageable with .38's, though.
Pick something your going to carry. That sounds absurdly obvious, but carrying a gun can be a pain in the arse. If you choose a hog-leg-boat-anchor, eventually you will tire of it and start leaving it at home. And that defies the first rule of gunfighting, which is to have a gun.
This safety, that safety, thumb safety, grip safety, free safety, add nauseam. The ultimate safety? The shooter...specifically the index finger on his/her shooting hand. If a certain type of safety makes you feel warm and fuzzy, rock on! I don't personally worry about my gun "just going off" while in my holster, nightstand, dropped from a plane, thrown around the garage, etc. I do know they go off when I press the trigger.
For you shotguns types out there, they are extremely effective, I agree. And NOTHING puckers butts and instills fear like the racking of a pumpgun. But, they are somewhat non-directional, i.e., they can throw a big pattern, and that's quite a few .32 or so caliber pellets travelling down range...and you OWN every last one of them. So be aware of it, your surroundings, and your backstop. Fortunately, I've seen advances in the "combat" shotgun of late, with advancements in chokes, tighter patterns, better rounds, etc., that minimize this problem to an extent.
Do NOT carry handloads in a carry gun! If you flip somebody's switch with a handload, and WHEN, not if, the civil attorney finds out about it, their going to be on you like white on rice, and make you look REAL bad!
Somebody mentioned "running away" as your first defense...and it was good advice. If you can, and you or nobody else will get hurt as result, unass the area, call the cops and be a good witness. We get paid to deal with deadly force situations, trained to deal with it, there's usually quite a few of us that show up, and have the resources ($$$) to deal with the ramifications of a deadly force incident. I'm not saying were all perfect, are better shots than you, are all that and a bag of chips, etc., but that is what we do. However, there are times you gotta fight, so be proficient with whatever gun you choose, fight smart and fight hard.
Now if you'll excuse me, I want to go look at a Glock 36. Al has piqued my curiosity in regards to the 36 and it's possibilities for plainclothes use. While I love my P7, if your gonna make a hole, make a big hole!
Justin