like bowhunting, maybe
Well, the advice on the .357 is about right, with it being considered minimal to boot. As far as "knockdown power" goes, since deer hit hard with serious rifle calibers still tend to run aways, I'd rephrase to effective or something similar and say 50 yds for the .357, 100 for the various .mag .44 and 45's. etc.
With iron sights, I tend to look at handgun hunting for deer as the near equivalent of bow hunting. It takes an exceptional shot to stay on the vitals of a deer much past 50 yds (9-10 inch circle)under field conditions, I would think.
I know I would be much more confident under 5O than over. About half that I would consider ideal.
Scoping a handgun, esp the rifle caliber single shot/spec pistols, changes that. But I don't really consider the scoped/specialty pistols handguns in the truest sense.
My dad had a .44 mag super-B w/ 10-1/4 bbl, scoped w/ a 2.5x and off the bench, we could brake clay pigeons w/ it at 100 yds. It was like a stockless carbine. When he hunted w/ it, he did not take a rifle. But you could not really put it in a hip holster and walk around w/ it comfortably either.