I believe the SMC is pretty much a commercial version of the Hungarian R-61 and RK-59. Pretty much the smallest 9x18 out there, not certain if there is a smaller .380ACP or not. They are very practical for pocket carry, but not a lot of fun to practice with.
Parts availability is another issue. Some Kassner parts might interchange, but there isn't a great deal of info available to determine exactly which parts wll. KBI in Harrisburg, PA has a few parts, including magazines, for the SMC pistols, but their phone number isn't published anywhere. I found it on a gunbroker auction for an SMC manual, the picture just happened to show KBI's parts line phone number. Mags for the SMC-380 ran $20 + $10 to ship.