What I have been sorely temtped to do is offer to pay someone that was willing to do the following with a hunting weight rifle and a non parallax adjustable scope-

1.Shoot 3 shots from a hunting position at a target say 300 or 400 yards away, in the hills-Shooting from sloping ground to a target placed on sloping ground across sloping ground.

2. move to another location, same range and conditions and shoot another three rounds from a hunting position.

3. Move back to first postion, repeat.

4. Move to altenate position, then repeat.

Wind meters not allowed.

I would really be interested in seeing the group size. I have never done this myself because having someone of my less than mediocre skills would be meaningless. I do have a pretty good idea of what my group size would be.
I have so little proficiency with a rifle that things like parallax, rifle cant, reducing wind drift through the use of a high BC bullet, rifle grip, velocity variations, bullet alignment are all factors in my shooting, and I know from reading here on the internet that a really good rifle shot has nothing but disdain for such trivia.
However, I think the test I have outlined above would be a pretty good indicator of a shooters ability to kill game at longer ranges.

Royce