Of the older Smith and Wesson metal framed autoloaders, which one was the most commonplace? If I had to guess, it would have to be one of the 3rd gen 5900 series guns. After the Beretta 92 was adopted by the US military as the M9, a lot of PD's started to adopt DA autoloaders. It seems that the 92, Sigs, and the 5900 series were really popular before Glocks and M&Ps took over PD armaments.