Been watching this thread because my new Shilen 6BR barrel seems to hate the 105 HPBT Hornaday that my X-Caliber barrel had an affinity for. So bought several boxes of 107MK to try out.
My results were very similar to yours. Best accuracy was 29.0 Varget and 30.2 cratered the CCI 400 severely. I didn't chrono it, but simply can't beat the results on paper. As best as I could measure it, the 3 shot group measured .08 (100 yds), so I'll go with that and reaffirm it with at least 20 rounds before putting the tuner back on.
Wish I still had access to a 500+ yard range, but developers nearby got a judge to shut it down.
Edit to correct primer used, CCI 400, not the Fed 205