I first bought a TBA-prefix 645 that I am very certain is completely original. I then bought a TBB-prefix 645. Comparing the two the TBB-prefix has variations in the stainless finish most notably on the barrel hood but also frame and slide (it also has a half-cock hammer) that I am concerned are the result of polishing. The brushed stainless finish appears identical to my TBA-prefix.
Were there variations in the stainless finishes, and did S&W install half-cock hammers at any point? The TBB-prefix does seem to have a higher round count so I wonder whether the barrel hood is simply wear. Thank you for the feedback and insight.
These are the best photos I could get:
TBA-prefix left, TBB-prefix right:
TBA-prefix top, TBB-prefix bottom:
TBA-prefix left/top, TBB-prefix bottom/right:
TBA-prefix top/right, TBB-prefix bottom/left:
TBA-prefix bottom/left, TBB-preifx top/right: