My experience is on Coues deer here in Arizona. It's been awhile since I drew a tag, so I haven't had much in recent years. My longest shot to date was 420 yards. I was fortunate to draw a late season rifle tag which puts the hunt squarely in the rut. The rut starts in late December and stretches into January typically.
On this buck, I had spotted the deer at some 1100 yards with my 15x binoculars. We watched a group of does for quite a long time expecting a buck to show up. Initially there was a small buck with them which we didn't know was a buck, but he acted like one. He was harassing the does but I just couldn't see antlers at first. Finally the sun glinted off his small rack just right and I realized he was in fact a small buck.
Shortly after that he took off quickly over a ridge. A bigger buck had moved in and I just hadn't spotted him just yet. Finally he showed and it was quite comical to watch that big buck tear up a prickly pear patch and harass the does a bit. Eventually he went over the ridge and chased that smaller buck back onto the side where he was spotted again.
It was getting into late afternoon and I knew we didn't have time to make it there. So using my range finder I ranged the next ridge close at about 700 yards and we made a plan to go to that ridge the next day.
We took our time the next morning and didn't head out until it was light so that we could find our way. Eventually we got setup where I wanted to be. Not too long after that the does we spotted the previous day started to meander in and as expected were about 400 yards away. Shortly after that the bigger buck from the day before showed up tailing a doe. He followed her into some brush and they were out of sight for a bit. Eventually came out of the brush and looking a little worse for wear, quite certain he bread that doe while they had some privacy.
He meandered out into an open spot near the prickly pear patch he tore up the day before. I ranged him at 420 yards. I took my first shot and as far as I know I may have hit Arizona with it or the bullet is still in flight to this day. Settling down, I lined up a second shot. At these distances, the deer don't scatter, they're kind of confused I think by what is happening and while they're clearly nervous, they don't head for the next county.
The second shot hit him square in the neck and he dropped on the spot. No....I was not aiming for the neck, but for the shoulder with a hold at his back line. Dead nonetheless.
The lesson learned is these long range shots are tricky. I had sighted my rifle in so that I knew the drop, but that was at Phoenix elevation of about 1000 feet. Not the 4000 feet or so we were hunting at.
It's a pretty big challenge getting the right setup to practice these shots and I don't think I'd attempt such a long shot again. I really don't care to lose an animal I know I've hit and so beyond 300 yards on these smallish deer is about as far as I want to shoot personally. The reality is no matter how high you may sight in, when the bullet gets that far the bullet drop at those longer distances is on an exponential curve and what would be relatively small errors at shorter distances are now amplified at longer ranges. And of course this raises the chance of a wounded and lost animal.