Just that in all the years I have been paying attention I have seen more Ms and Ss.
Might be just my neck of the woods and wouldn’t be surprised if the Kurz production mirrored the standard Oberndorf action with Bs being most common, As the rarest and the full stocked rifles somewhere between.

I’ve had two Kurz mausers, one an S and the other I could swear was also an S but have forgot and haven’t found the pictures of it. Remember it had really nice wood for an original Mauser though.