Not every cop carries a backup gun.
Some feel that the added weight can be a hindrance, and that extra magazines and the mandatory carry of less-lethal options (i.e., Tasers) reduce the need for a backup gun. But I feel that carrying a second gun is well worth the effort in many instances. For those who do decide to carry, the first question is often “revolver or semi- auto?”
Because backup guns are not standard-issue with some police agencies, officers have a wider choice of options. Though many prefer to carry a subcompact version of their primary weapon because of the ammo, magazine and fire-control commonality, there are reasons why revolvers are preferable even when the primary is a semi- auto.
Yes, revolvers can have shortcomings as primary weapons, but these weaknesses are less apparent in situations in which backup guns tend to get used. And when will you resort to your backup? When your primary becomes non-functional or runs out of ammo, during an attempted or actual disarming, or if you need to arm another person.
Compared to semi-autos, revolvers are mechanically more reliable, more forgiving of operator error and simpler to operate under stress. With revolvers, there’s no chance of limp-wristing and creating a stoppage, no magazine to accidentally release, and no slide movement to impair the action if it is blocked or if ejected shells bounce off something and back into the ejection port. Yes, elementary gun handling skills prevent some of the operator-induced mistakes that can cripple a semi-auto. However, a backup gun often comes into play when an adversary has grabbed your primary pistol and placed you in a life-or-death struggle as the assailant attempts to disarm you. In those scenarios, you won’t have an ideal firing grip, the mag release may be accidentally hit or the slide may be pressed out of battery, creating a stoppage on an autoloader during a struggle. Contact shots can do the same to autoloaders, and those shots are likely to be the type you will take in these circumstances.