Well it really varies in what country you ask for. In the United States and other western countries, guns were carried from around 1850s, but in the 1895 a law was passed which made it compulsory for...
In the U.S., different police departments use different guns. As far as handguns go, Glock has 60% or so of the market. Sig has a pretty good percentage of the rest, and there are a few others that...
Each police agency has their own set of requirements for hand guns. ------------- It depend on state, station or personal preference. In U.S, Most use glock 19s 9 mm. Some use berretta 92fs 9mm