Why do I always link the Glock handgun to a er gun. ?

I have been a police officer for 13 years and the city I work in has a had a real bad gang problem in the past. As a police department, we carry the .40 Glock, but in those 13 years, I have only confied 3 Glocks from "ers". One of those three was stolen from a police officer's home in a burglary. Most guns we recover are either revolvers or 9mm generally.