In 1997 or 98 my OIC had me do a project to see how many officers approx. 8500 , were still qualifying with their revolver.The dept started issuing the Beretta in approx. mid 1989. So about 3500 to 4000 people on the job who had originally been issued revolvers. Officers could take a transition class as semi autos were first approved in mid 1986, so a training cadre, and transition schools had to be set up. I think classes started sometime in 1987 or so.
That gives you an idea of amount of officers as by late 90's most officers had the chance to attend S/A transition school if they wished. This was a 2-3 day school and had to qualify every month for 6 months with their 9mm be it Beretta or S/W. Anyway my audit showed that about 270 officers were still using their revolver to qualify, however about 1/3 of those officers were 9mm trained and carried that weapon but found it easier to qualify with their revolver ( a large portion of these were females) nothing implied that's just what I discovered, due to several rounds having to be fired with the weak hand , the longer and firmer 1st trigger press may have been the issue. Remember this was before we had computers so this was a labor intensive qual card and approved weapon hand search. As soon as computers came into play the rules were changed to insure you qualified with what you were carrying .
Clearly most officers preferred the semi auto for firepower and ease of loading.
Ammo being 38+p 125 gr SJHP rev or 115 JHP for semi .
I was a hard core revolver guy. Before going to the Academy ,I carried a model 6" 14 in a left hand Bianchi Judge holster, with a S/W 3914 in a special made pocket holster in my right front pocket, the holster had a forward pointing clip , so that the pistol sat up in my pocket, with just a bit of the grip and mag showing , but I covered it with my radio, and usually had my hand , thumb in my pocket , on the gun. I had the rear sap pocket of my pants sewed up short and it held an extra magazine.
When I transferred to the academy went to S/A carry as that was what we were teaching. With me it was never an issue of not being confident with a revolver, even at that time I already had 15 years of serious PPC shooting under my belt, it was about firepower, and the advantages of the Beretta( later a PC 5906) in a combat situation. Reloading a revolver, running, in the dark, or laying on your stomach is way more difficult than with an autoloader, I don't care how much you practice. Add the ease of putting night sights and lights to the equation and its really no choice for modern LEO.