By those days standards that was "well armed", some police and some criminals carried semi-autos, the 1911 was obviously popular being the military issue sidear

By those days standards that was "well armed", some police and some criminals carried semi-autos, the 1911 was obviously popular being the military issue sidearm since that year, but it wasn't common. And a shotgun is a fearsome weapon at shorter ranges, out to 100 yards or so; it's just that an AR-15 is better for almost all police purposes, ditto for civilians for self-defense. And in the long run, I suspect trading their khaki for body armor and the disdain or worse of civilians will be viewed as a mistake.