My longest ever revolver shot was about 180 yds (iron sights) with an 8 3/8" 357 & the 150 gr Sierra JHC, this was about 40 years ago when I was dumb & reckless....I'm still dumb! Anyway it was a lucky shot on a fork horn muley, I hit him at the base of the neck with the second shot. We measured it using the old bill of the hat method, measured it twice.
Took a cow elk 5 years ago at 168 yds (iron sights) using a Ruger OM 45 & the 260 gr Keith slug over 23 grs of H110, she was standing in deep snow & stood out like a piece of black coal.
I try really hard to stay away from the long shots when possible though, handgun hunting to me is getting as close as possible & making a clean kill with one shot, taking multiple shots & killing isn't good shooting skill, its luck.
My longest shot with a single shot scoped handgun was a doe antelope in Wyoming at 444 yds using my 6.5/284 Encore, this was a 15" Bullberry Barrel, we lasered it after the shot (one shot) its very hard to get a rangefinder reading on antelope at extended distance. This gun had a 3X12 Burris on it, also used the same setup in Africa but the shooting was close.
I've taken rock chucks out to 500 yds with various single shots, to me the challenge in long range shooting is the wind, once you know the distance with a rangefinder you should be able to make the long shots with great consistency. If it takes more than 2 shots, thats not long range accuracy, thats long range luck.
I've witnessed Ken ONeill shooting long range chucks, he's a master long ranger!
One time we were getting ready for a long range rifle match & I entered using my 15" 7/30 Improved, the distance was 500 yds at a water filled gallon jug. My buddy & I practiced for a couple of weeks getting ready. The day before the match we had 4 steel targets set up at 500 yds, one was a full size ram, 2 were pigs & one was a chicken. I went 4 for 4 using that Bullberry 7/30 Improved & 120 gr Ballastic Tips.
When we got to the match the next day the water jug was on a table up on the side of a mountain...way above us, because of the steep angle the shot was very tricky, behind the water jug was heavy brush so no one could see the shots, 11 of us missed it twice each, on my 3rd relay I hit it & won the match.
Dick