I no longer use nor see a need for an AR, but such thing are always situationally dependent and for me it would almost certainly would be very close range.

For legal and ethical reasons, I would highly recommend avoiding shooting someone if at all possible no matter where you live or what your local laws happen to be. If you follow that advice, the odds of a civilian ever needing to make a long range shot with an AR-15 or any firearm are so astronomically low that it isn't really worth giving it much thought as there are so much more important things to focus on in terms of personal defense.