Resurrecting an older topic cuz I've been at this long enough now to have an opinion...
I agree with RM's last post, but would add that an SKS offered for civilian sale that cannot be placed back into military service without alteration should be considered a commercialized carbine. But, if it can be taken from a civilian's collection and placed directly into military service, then it should be considered a milsurp.
I do not feel that simply scrubbing the gun or changing SNs constitutes altering it from its original military purpose. However, doing so can make it much more difficult for collectors to determine its true pedigree...