Great shooting. I have quite a few 1 hole groups that are unreal.
However, I like to consider the measure of accuracy as the worst group that a particular rifle/ammo will shoot (within reason of course, my jerking the trigger and making a 1ft group doesn't reflect on the platform). If a rifle and ammo's worst group is 1/2moa that is extremely good. A rifle that shoots a .2 group @ 100 yards once in 25 groups, while the others are 4"...that isn't as good.
That way, I know for certain that my accuracy is at least [this] good.