How could or should the 6.5 mm Grendel be improved?

[stanc]

I am not exactly sure at present. The result will stem from the target definition and the hit probability ie the required carried kills.

Gut says maybe a 6.5 but i would prefer a 7. Keep the OAL short and then work back to the case volume for the optimum operating pressure at an acceptable fill level with the new powders.

That sounds reasonable. In the absence of test data that shows 6.5 would deliver adequate terminal performance, I'm inclined to think 6.86 or 7mm might be necessary. However, that's just a gut feeling.