Just my 2 cents:
How about find a bullet that shoots good say 75 ,80.85,87 grain in your gun and stick to the most accurate
one that way you don't have diferant inpacts etc just one good load for all?
I have read some place about the 70gr tnt hp by speer shotwith a 6mm-284 with that twist was ok, but others I am not sure. I never tried any smaller in mine I am working from 87- to 105 gr bullets with mine