I know there has been some discussion on trigger stops, but I can't seem to find archive posts regarding my specific points of interest.

I have a 586-3, serial prefix BFW, that has no trigger stop cut in the frame behind the trigger. I have a 686-3, serial prefix BHE, that has the stop cut and the stop held in place with a screw as was done in earlier generation revolvers.

With one having the stop and the other not having it, do these two revolvers span the time period of the reintroduction of the trigger stop as a more or less standard feature?

I'm more surprised the 583-3 doesn't have a slot in the frame for the trigger stop.

I don't recall a time when they reintroduced the trigger stop but they were standard when the revolver shipped with a target trigger.

Does your 686 have a wide target trigger and the 586 a smooth combat trigger?

The 686 has a wide smooth trigger; the 586 has a narrower smooth trigger.