The 8 shot model 627 was introduced early in 1997. The locks did not come into play until after Sat-T-Lok bought S&W from it's British owners in 2001(?).
So there are 5-7 years of non-lock production.
None of these 5 have locks including the blue steel, 8-shot, model 27s that were re-introduced in 2000.
Many other variations of the 8 shot model 27 family have been made over the years. There are the V-comps that fly rodder makes reference to. These were introduced in 1999 as an exclusive offering for RSR.
Then there is the 627 Heavy Hunter. Introduced back in 1998.
Still more that I can not recall. If you really must have a no-lock, just keep your eyes open.
NONE of the Performance Center model 27/327/627 revolvers were ever manufactured with MIM triggers or hammers. Those are forged.