I'm sure that would work if it comes down to it. If I can't find the proper baseplates given enough time I may look into doing that. For the time being I don't really intend to carry this gun nor use it in competition (I used a Ruger LCP and an M&P 9L for those, respectively), so I'm not too terribly worried about it.

Not sure, but it also could be the date of manufacture. I don't know if S&W's really old baseplates were thicker or not, but my Sigma mags are all Law enforcement only marked so they're from at least before 2004.