Just remember, S&W used to sell the target triggers and hammers to their dealers in bulk and then later on, as accessories bubble packed on cardboard hangers.
At one time, the hot ticket for police officers and sheriff deputies in east and central Alabama was a M19 or M66, with target hammer and trigger. I changed over a pile of revolvers to the TT & TH configuration for my fellow LEOs.
As time went on (mid 1970s into the 1990s), more officers wanted the smooth triggers (.312 and .400), instead of the serrated target triggers. I was happy to oblige, selling them the parts they wanted, and usually keeping the older, narrow grooved triggers.
Then, cops went to semiautos, mainly Glocks, and the revolver modification market for LEOs went south.