I have this 1951 vintage (K135728) K22 CM. It has all matching numbers and is in really good condition. The one thing that has me puzzled is the "frame stop notch" hammer like on the 2nd model K-22 Masterpiece (pre-war). Is this normal? It seems that the difference is my gun does not have the flat face hammer but does have the frame stop notch. My disadvantage is I have not seen any of these early post war Combat Masterpieces before.