The semi-automatic has the following features going for it as a concealed weapon: flatness, greater number of rounds between reloadings, faster reloading (when spare loaded magazines are available to hand), the potential for better accuracy in average hands (although that point is more or less moot at average man on man confrontation distances) and enhanced reliability when neglected or subjected to dirt.
The revolver has the following features going for it as a concealed weapon: less ammunition sensitivity, simplicity of operation and less physical strength required from the operator.
Looking first at the revolver, although double action revolvers are more complicated, watch-like mechanisms in their operation, nothing else is usually required – assuming the gun is loaded, which is simpler than loading an automatic – than to point the weapon and pull the trigger.
Certainly, most double action revolvers can be manually cocked and, if not fired, the hammer must be lowered. But, if the operator is taught to use the weapon properly in the defensive context, most of the time the weapon will – hopefully – never be manually cocked unless at the target range. So, to make the gun go bang, the cylinder is swung out, cartridges are loaded into the cylinder (they can only be loaded bullet end first) and it’s usually pretty obvious if a cartridge is too big, small, long or short for the cylinder’s charging holes.
The cylinder is closed (even flicking the cylinder closed, a potentially damaging practice in which some movie private eyes of old were wont to indulge, would have to be done a lot in order to render the revolver inoperable) and the gun is pointed and the double action trigger is pulled.
If the operator changes his or her mind while squeezing (more like pulling) the trigger, easing trigger pressure will let the hammer down with insufficient force to ignite the primer; and, anyway, hopefully the revolver was originally pointed at something or someone that needed to be shot. When the gun has been fired five or six (or more, these days) times, it will click, just like in the movies, but no bullets will come out and there will be no noise other than the click. Our inexperienced operator realizes that the weapon is empty and elects to reload or leave the gun empty.
The double action revolver is simple.
No great level of physical strength is required – especially hand strength. If the operator has trouble with recoil from something as mild as a standard velocity .38 Special or a .32 S&W Long, .22 Magnum revolvers exist. Even a .22 Long Rifle double action revolver can serve, when needed. So perceived recoil becomes a non-issue, one way or the other.
As long as the operator can lift the double action revolver into a firing position, even an extremely weak person who could not successfully complete a double action pull can, out of necessity, cock the hammer of the typical double action revolver and exert the miniscule amount of finger pressure required to pull the single action trigger and fire a defensive shot. In short, double action revolvers are a no-brainer to operate and can be successfully manipulated by almost anyone, regardless of sex, age or physical health. And, under normal circumstances, they are ridiculously dependable, despite their greater degree of mechanical complexity.