In the Southwest, a well-intentioned good guy who was apparently a little ambivalent about his choice, decided to carry a gun. He purchased a Glock 23 and kept it in a fanny pack, loaded with a magazine of .40 S&W training ammunition but with nothing in the chamber.
The day came when he was faced with armed robbers. He grabbed the Glock out of the fanny pack and tried to chamber a round but fumbled with the slide and jammed his pistol. The robbers shot him down.
He survived--and sued Glock, Incorporated.
In the Southeast, a jeweler decided to augment his alarm system and security cameras with a gun on his person. He chose a Walther PPK .380, carried with a round in the chamber and on-safe, and virtually never practiced shooting it. His own security cameras captured the chilling moment when he pulled his .380 on a robber who had walked in with .38 revolver in-hand. In the chilling video-tape, the jeweler can be seen to whip out the little auto, point it at the gunman, and pull the trigger repeatedly. The pistol does not discharge. The gunman is then seen to extend his arm toward the jeweler and pump him full of lead with the revolver. The jeweler falls and the robber flees.
The jeweler survived to admit he had forgotten to release his thumb safety. When asked gently by an interviewer if he had ever practiced with his gun, the jeweler replied indignantly and defensively, "Hey, I'm not Rambo!" He blamed the gun for losing the upper hand his obvious courage had earned him, and reportedly now carries a Smith & Wesson .38 revolver.
The last two cases remind us that often, it is user-error that causes the gun to fail to shoot when defensive fire is desperately needed. A man not confident enough in his ability to carry a chamber-loaded semiautomatic pistol is better served with a revolver. Operating the slide before firing is a complex psycho-motor skill of the kind that does not survive stress well, and it's normally a two-handed operation. The history of gunfighting shows us at least half the time, we will fire our handgun one-handed when attacked by surprise. The gun must be in a condition that allows one-handed operation.