Savage, you'll find it pretty straightforward to hit out to 400 yards, if you shoot "normal" calibers that is, but then it starts to get exponentially harder after that. Maybe not truly exponentially harder, but you get the idea. There is, in my opinion, a world of difference between 500 yards and 600 yards for example... in my case, about 4 or 5 months of diligant practice, at least once or twice a week, to extend from 500 to 600. It's the wind.
At 400 yards you can just wing it pretty much as far as wind. Add a little seat-of-the-pants Kentucky correction and you'll be fine in reasonable conditions. Not so at 600- again just IMHO and shooting the stuff I shoot (bullets in the high .4's to low .5's as far as BC).
I THINK, don't know this for sure, but I THINK that if you use obscenely high BC bullets, the range at which the wind is a non-factor is extended. However, most of those bullets are inappropriate for hunting and might be a real problem if the shot turned out to be 50 yards away!
As to the ethics of shooting XXX (or even XXXX) yards at game, that is an unavoidable topic in a thread like this, I suppose, but that's been beat to death and then some so the more we can leave it lay, the better? :-)
