I worked in the Chicago 'burbs (started in 1978) and many of our guys either came from CPD or went there later. Recruits had to buy their own guns; everyone I knew went with the Model 10 (today, recruits have to buy and carry the Glock 17) until after they were off probation, then the Model 19 or 66 (if you could find them) became the gun of choice. Some guys carried Colt Troopers or Pythons, but the duty gun had to be a revolver capable of shooting the city-issued ammo, WW 158 grain LSWCHP+P, the same stuff we carried in our issue M15s. Back-up guns could be anything, hence you would see guys in uniform carrying a Model 10 on a duty belt (that's never taken out of the holster) and a M29 or 1911 "back-up" gun.