Re: two grouping?
I don't know your problem for sure. But I wonder if you wear glasses?
I have had this same issue recently with guns well capable of better performance. Another 'clue' toward resolution IMO, is the fact that I shoot better, and better, the further out I go. And lastly, these occurances began with my astigmatism and eventual prescription.
I wouldn't be surprised if the answer to this might finally resolve the 'shrinking MOA' phenomenon.
Personally, I think it's parallax caused by less consistant eye position -shot to shot, at shorter ranges. I think my brain compensates for less than perfect focus up close(100yds), at high power, because it can.
But this is not the case 300 or 400yds out. I am forced to position for perfect focus, and this is leading to more consistant results.
Just throwing out ideas