I have been working through this topic for years and there really doesn't seem to be a consensus.
If bullet A needs so many hundred yards to settle down, why doesn't it do so in EVERY rifle?
If a bullet is wobbling under such enormous force, how can it not start to diverge way off course at least once in a while?
Like a football, things usually get worse with time/drag/deceleraton. ?????
If a bullet 'steers' back into the group, is it now going to drive away from the group at further distance? ie some further distance is a crossover point with bullets (smaller groups compared to closer ranges) continuing on their way diverging from the group?
I have no answers.
The only answer that makes sense to me is optical related. Because of issues like parallax, maybe even focus, we see proportionatly 'worse' at close range then at far. Again, I have no way to back this up as I have not seen this phenomenon myself.
Interesting though. Have there ever been high speed photography on the subject.