How could or should the 6.5 mm Grendel be improved?

[Tony Williams]

A 6.5mm lead-free bullet could weigh 7 g (108 grains), maybe a bit more. That's 75% more than the 4g M855, while the 9.5g 7.62mm M80 weighs only 35% more than the 7g. So even if all else is equal (unlikely, given the very ordinary performance of the M80), the lead-free 6.5 should be very much closer in effectiveness to the 7.62mm than to the 5.56mm.