Did you shoot the three groups in order, left to right? I wonder, because sometimes it takes us a few shots to get to where everything is comfortable and it all sort of comes together. Neither of those first two groups is worth rejecting; I think I would try them both again, and maybe move up a half grain or even a full grain if you aren't at the top of the spectrum.

But I would agree: that rifle of yours REALLY likes the 70s!