I don't understand what a 6.5mm Creedmoor machine gun would be used for? What introduce yet another cartridge choice and logistical requirement? Need 5/56, 7.62, .50, 9mm, .40s and now 6.5mm ......

Wouldn't this MG only be sensible if all the common rifles also were upgraded to 6.5 mm?

And yes, the Swedes had it right, with the original a hundred years ago.