Army Times article on new cartridge for SAW and LMG

[stanc]

That was my point which makes the round larger to handle the larger powder charge defeating the intended purpose. Which is what I meant when I said it will need more horsepower. 6.5 will always have a higher sectional density with equal bullet weight. Which will give better penetration with similar bullet types.

As I understand it, the round doesn't have to be larger to get the same (or better) performance with 6.8mm.

To have the same sectional density and BC, a 6.8 bullet needs to be only slightly heavier (~135gr vs 120gr).

The larger "piston area" of the 6.8 bullet allows it to be pushed to a higher MV, vital for body armor defeat.

The greater weight of the 6.8 projectile enables it to have higher retained energy at long range, also critical.

For the intended goal, 6.8mm is definitely the better caliber.

Whether the goal is realistically achievable is another matter.