The longest whitetail shot I've ever took was 603 yds. according to the range finder.
That was with Hornady A max bullet, 175 grain, pushed through a Reminder 700 in .30-06, light weight mountian rifle with skinny barrel,
I don't remember which powder, I was starting to use Varget, but I honestly can't remember.
I won't lie,
The deer dropped right where it stood, the shot placement couldn't have been better, and with that rifle at 603 yds it was 1/1,000 shot.
It wasn't a heavy barrel, it wasn't a bench rested shot, it was the factory cheap plastic stock which I hadn't worked out yet.
I did use optics, a fixed 6x Leupold I've had for a couple decades.
If it wasn't the last day of the season (I got there late) I probably wouldn't have taken the shot.
I was using a brush buster round (175 grains) so I wasn't expecting to make a 600 yard shot.
The only bad part was, it was in the serious mountian in West Virginia and it took me three hours to get it to the truck.
600 yards in a straight line across a gulley can take an hour or more to climb down, then back up over there in gulch country! I worked my butt off for that deer! Kind of a skinny 6 pointer, but last day of season, beggers can't be choosy...
I've only done the high planes a couple of times after antelope, it's a workout!
Elevation + out of shape + beer = an exhausted idiot chasing switching tails!
No UTVs back then, it was Jeep or boot leather... Couldn't do it today.
I threw a 168 grain in one side & out the other, the guys clued me into 125-135 grain bullets, they weren't chasing them, so I listened.