I was basing that off of what you had shown other FMJS do when they do not frag. Wouldn't a larger diameter bullet create a larger permanent wound path given no fragmentation or expansion from either. Upsetting the larger, longer, heavier bullet wound create a larger wound path than a shorter, smaller, lighter bullet again assuming no significant expansion nor fragmentating.
All spitzer type rifle bullets yaw in tissue. The question is always how deep do they penetrate before yawing and how large is the PC and TC are at that point. Longer, wider, faster bullets make larger holes and greater stretch when they yaw.
I suspect a 6.8 mm FMJ will be somewhat like a 7.62x39mm lead core FMJ.