what would you do next?

[jrock]

I had this same thing happen on my .243. I would shoot loads at 400 yards and a .2 grain difference cause a low ES/SD but wide group while the other was 1/2 MOA and wide ES/SD. Tested on several different days to verify and got the exact same data each time. Haven't really bothered with it much since as I trust the results on paper more than my cheaper chrony.