Yesterday I went in local gun shop and he had two NIB S&W MOD 10's. Both round butt. One was snub, the other 4" tapered. I bought the 4" Question: my new gun ser# CCK35XX has firing pin in hammer and was dated at 1998 production. Snub had ser# CDBXXXX with firing pin in frame. Does that mean S&W started with firing pin in frame approx. 4 or 5 yrs. ago?