Ive taken 1 deer past the 400 yard mark with my 308, even with 4x magnification that deer was still pretty small, probably the biggest thing id be worried about shooting at that long of distance is exactly what happened to me, something called time of flight I was lined up on that deer and just as i pulled my trigger it took a step or two forward in the time it took the bullet to get there, my bullet struck it square in the guts, i thought it was good hit because it took off running and folded over after about 40 yards but when I retrieved it the deer had a hole in its stomach and intestines hanging out of the exit wound, when i field dressed it the intestines were perferated stomach was busted open the smell of the mixture of bowl and stomach acid is enough to make some of the toughest men puke I was having the dry heeves the whole time. The only vital organ somehow or another that was hit was the liver so the massive internal hemridging would explain why it expired after only 40 yards of running.

Nowdays I try to keep my shots as close as possible if I have any doubts I dont shoot.
I've learned to avoid the smell of the mixture of bowl and stomach acid at all costs just thinking about how bad it smelled is making me gag right now.