Carried a S&W 586 357 mag the first 5 years of my LEO career. Practiced A LOT, and was very confident with it. Saved my life at least once. For the remaining 24 years of my career, it was a semi-auto in one flavor or another.
Learned a few things...
Revolvers do malfunction. Bad reloads, high primers, debris, loose ejector rods, broken parts / out of time..... It happens. Same can be said for autos as well.
Reloads. The 5 or 6 shots in a typical revolver is usually all you will ever need. Usually... But, if you have to reload, you are already ahead of the game if you are carrying an auto with a higher capacity. I have seen a lot of guys under the "pressure" of qualifying pop their speed loaders too soon or out of alignment, dropping all their round on the ground. Embarrassing. Deadly in a real gun fight. A lot quicker to pick up a dropped magazine, and slam it in the gun.
Clearing a "jam". In a revolver, a "jam" is usually caused by high primers, debris under the ejector Starr, or a bullet pulling from the case under recoil.. All of which can be difficult and time consuming to correct. With a typical service auto, "Tap, Rack, Bang" (Or the more politically correct Tap, Rack, Shoot if Appropriate) usually suffices, and can be done quickly.
Back in "the day", semi's were not generally as reliable as revolvers, especially using hollow point ammo. That has changed, and modern semi's like Glocks and SIG's are extremely reliable. Used to be able to get all the duty ammo I wanted, in any quantity, free. Spent quite a bit of time seeing how many rounds I could shoot out of a personal Glock 19, as well as a Gvt. owned Sig 226 and Ruger P-85, without cleaning. After many thousands of rounds, the Ruger suffered a magazine lip failure (crack). The Sig was still running fine last I seen it after many many thousands of rounds, and many student agents. My Glock 19, I finally gave up on, and cleaned, as I have retired, and am running low on free ammo to waste.
Today, when I carry my old 586 under my jacket, I feel well armed. When I carry a Glock, I feel more so... Of course, there is always a Ruger LCP in my pants pocket, just in case.
Larry