For a hunting rifle? I would say 5-6" group at 100 yds should be the max. I' much prefer <3".
In my 40 + years of hunting, with all the animals I've harvested, I only shot 3 animals that were 300 yds or over (not counting groundhogs or crows). One each, antelope, whitetail, mulie. There are few instances where you just cannot get any closer.
Don't take the shot unless you have practiced at that range a lot under different conditions. Wind can play havoc on a bullet at that range.