Alternative to 6.5 Grendel?

[Tony Williams]

Thus a 6.5x45 would do well as a replacement for both the 5.56x45 and 7.62x51. And then use the 8.59x64 (.338NM) in the med MG to replace the .50 cal M2.

Most of the troops would not need a long range weapon (20 inch barrel for the DM) and would only use 16" carbine. But a 6.5x45 would give the penetration at close quarters that the 5.56x45 does not have. The 5.56NATO is just too light to go against brick or stone buildings. Russians found that out with the 5.45x39 in Chechnya.

Quite so. The point about long-ogive bullets is that they provide long-range performance for free. Just compare the 6.8mm Rem SPC with the 6.5mm Grendel: they are about the same size and weight, and develop about the same muzzle energy and recoil, but the Grendel has been designed to take long-ogive bullets while the SPC cannot. As a result, the Grendel is a good long-range cartridge while the SPC is limited to medium range only.