Not only are they 8 rounders, but they also look shorter than the standard 9 round 10mm mags. I'm not familiar with any mid-sized frame 10mm guns from S&W, so if I were to speculate, they are for some type of experimental 10mm semi-compact that never made it into production.

Who knows, maybe S&W made up a few "1013s" for testing but killed the project when the 10mm lost favor and was discontinued...

__________________
My sgntr is mor thn 30 chrctrs