Well, for what it's worth, I have an early Smith PPK/S that has been quite reliable over the years, with one caveat: Smith changed the beavertail to eliminate the slide bite. When they did that, they also "tweaked" the dimensions of the grip. This, in turn necessitated a change in the mag. Point is, aftermarket mags made for the Interarms and German guns will not work!!
I found this out only after purchasing four Mec-Gar mags!! As long as I use the mags provided by Smith, the gun works like a charm!!
This leads me to believe that some of th jamming tales of woe heard are because people don't realize this and try to use aftermarket mags. I suspect that even the "new factory" mags from Earl's will not function in a Smith gun!!