I wrote the above in my previous message and thought I should explain it some more.  Hollywood has ruined the general public's understanding of what the handgun can do.  We have both good and bad ideas about handguns.  On one hand the general public is scared witless of them, but the facts are that most handgun wounds are survivable, given the high level of quick medical response and care in the US today.  Handgun wounds can be debilitating but they are not immediately so.  This means that when a good guy (or law enforcement) chooses a gun and cartridge meant to stop bad guys from committing terrible acts, they must rule out cartridges that will (only) eventually debilitate or even kill, and concentrate on rounds which will, as much as possible, stop the individual right away.  Even with good choices made in this area, there are reason this does not happen regularly.  To whit: 

One is because shootabilty limits the power we can use in a handgun.  There are very powerful handguns that are very close to the mythical one-shot stop.  these are mostly large magnums.  About the only magnum that is shootable is the .357 Magnum, and only in a full size service revolver, which almost no one is willing to carry anymore.  But having lived through the era, let me tell you that in its heyday, the .357 Magnum service revolver enjoyed a stellar reputation in law enforcement for being a one-shot stopper.  (This is why there was so much effort put into the development of the .357 SIG, which didn't and doesn't quite measure up to the Magnum). Nothing else came close and nothing else comes close now. Today we have focused more on shootability, which means less powerful rounds with which we can fill the air.  This has encouraged less accurate shooting since everyone is carrying a dozen to 1 1/2 dozen rounds in their guns.  Subconsciously this has led to poorer marksmanship. 

This is the second reason handguns do not regularly stop bad guys--poor shooting.  Unless you can put your bullets into the major blood-carrying organs--spine or heart, or the brain, you are unlikely to stop the physical plant, and thus the attack.  Yes, good marksmanship is a necessity.  We've fooled ourselves for a couple generations by telling each other that general "center mass" shooting is good enough.  We need to be able to shoot fist-sized groups or smaller where we want them to go at any range.  If we can't we shouldn't pull the trigger.  I'm going to be judgmental and say that most handgunners I see practicing appear to be satisfied with unsatisfactory groups--this under picture perfect range conditions, not under conditions where someone is trying to kill you. 

I believe this last thing is the crux of the reason people carry unsatisfactory handguns--they don't really and truly believe they will ever have to use them, thus they let themselves be satisfied with guns that are too small to be truly shootable, using cartridges that are not capable of stopping an attacker immediately, by shutting down the physical plant.  Again, it takes a service cartridge and good marksmanship under fire.

What's acceptable for concealed carry?  The individual must decide for themselves, but the criteria he uses to decide should be honest and realistic.