To post #9 (and as already stated from Toolguy and iPac in posts #10+11):
It seems, the trigger do not "reset" correctly (= in it's fully forward position).
Here -Thanks to 500 Magnum Nut !- scroll down to "Side plate removed" is a picture, how it should look...
FAQ
and here -Thanks to armorer951 !- the difference between DA / SA can be seen:
Revolver action drawings
For disassembly / reassembly the old(er) S&W-Revolvers this may be helpful (HINT: Don't disassemble more
than necessary, especially let this "trigger/hand/ handspring-thing" together
):
1.
American Rifleman | Smith and Wesson Model 29
2. the pictures to 1. (Click on the white arrows in the Gallery)
American Rifleman | Smith & Wesson Model 29 Exploded View
Hopefully a good cleaning (with a toothbrush) and a light oiling will solve the problem...
Otherwise perhaps the next step should be a new Rebound Slide Spring...
Good Luck !
P.44
Attached: My father's M 66-1 (from 1979)