It'll work for Deer ( if you make a good shot ) out to 50 yds ....but I sure wouldn't go any further than that....and only that far, if you practice a lot and can make that shot 100% of the time into no bigger than a 9" circle.
I practice with a single action Freedom Arms revolver, in .357 mag, at 25 yds at my local indoor range ( that's max distance at my range) ....with a 6" bulls eye...and I can hit it 100% at 15 and 20 yds....and about 90% at 25 yds (when I'm dialed in) with my eyes... but I don't know about 50 yds with open sights. If I were shooting at a 9" target at 25 yds...I'd be 100% ....but that's a pretty good shot at 50 yds with open sights.
My gun will shoot a 1" group at 25 yds from a rest.../ but I can't do that standing unsupported with a 2 hand grip. Its me ...not the gun .../ now you can certainly practice from a supported position ( like leaning against a tree / or holding the gun in the crotch of a tree ) and that'll tighten up your shot...