Question: Early stainless trigger/hammer

[schneiderguy]

Correct me if I'm wrong, but this is what I've picked up from reading posts at this forum:

Early Model 60s had stainless triggers and hammers. Due to issues with the parts, S&W changed to flash chromed carbon steel after a small production run of stainless parts.

This makes sense, but recently I acquired an early Model 67 (1972) that has a hammer and trigger stamped with "S", which according to some posts I've read on here means that the parts are made of stainless steel. However, the appearance of the parts looks identical to the flash chromed parts in later stainless revolvers that I have, which are not stamped "S".

Then, I was reading in History of Smith & Wesson by Jinks, 1977:

The first [Model 60] revolvers completed were manufactured with a bright polished stainless steel finish on the frame, barrel, cylinder, hammer, and trigger. However, the material used in the hammer and trigger was not sufficient hardened; and, in 1966 when the hammer and triggers were case hardened, producing a dark finish, the process changed. [...] The problems with the hammer and trigger were corrected by flash chrome-plating these stainless-steel parts after they had been heat treated, resulting in the type of finish currently offered on this model

Which seems to state that early flash chromed parts were in fact still stainless steel, which explains the "S" stamp on my Model 67.

Is this correct? Or do we now know something that Jinks didn't when writing his book?