The one thing that you can count on is that you cannot count on anything. For the patrol officer to the undercover detective, counting on simply your primary weapon can be risky. Sure, it may have worked every time you have used it
in the past, but you never know when this mechanical contraption will break down. As a result, having a backup gun is more than a luxury—it is a necessity.
The first decision will be what to select: revolver or semi-automatic? I personally prefer pistols, but a revolver is a very viable personal security firearm. The primary reasons most will select a pistol will be ammunition capacity and a slim profile, which are definite advantages. But once you decide on a pistol, which model do you buy? When it comes to firearms, size matters. You want a backup gun to be a “handful,” a gun that is small enough to conceal and carry without unreasonable effort (effort will always be required), but large enough to fill your hand and powerful enough to use in a fight.
This is a tall order when you stop to think about it. These days I find that a single-column 9mm pistol might very well be the optimal choice. When loaded with street-proven ammunition, the 9mm can be an effective fight stopper as long as I do my part, and with a capacity of seven to nine rounds and the ability to quickly reload, I should be able to handle all but the most extreme circumstances.