Total comfort confidence zone is 300/350 yards. My under ideal conditions with a solid rest is 400 to slightly over.
I don't doubt that I could learn to get em at further ranges but I haven't had the time and or resources such as a 500 yard or more shooting range and learning the finer details beyond Kentucky windage for long range shooting. Even with that I don't believe I'll ever shoot at game animals much beyond 500 yards if I ever even do that. For me personally there is a line where hunting stalking skills diminishes that I'm not willing to go beyond. That is a personal thing and I don't decry those that do otherwise.