As an old fart (76) I just can't see the iron sights anymore. So I have red dot type sight on my S&W629. I am comfortable taking a shot at a deer in a pinch up to 150 yards, but normally only to 100 -110 yard. (mid range trajectory is 3" high, 3" low at 120 yds). On my .357 S&W 686-8 I have a 1X-4X scope. With a rest I am comfortable shooting at deer at the same range. I usually only take neck shots. Successful so far.
The difficult part of the red dot is that the dot covers so much area it's difficult to accurately sight it in. The dot is bigger than the black on a 50 ft pistol target at 100 yds.
My two cents