Grendel as a Universal Infantry Cartridge

[stanc]

The problem is that M240's and SAWs are difficult to get into action because of their weight and bulk, compounded by the disparity in fatigue the gunners experience in relation to riflemen carrying M4's...so when contact happens, the guys with the lightest blasters are the most able to assess the situation, maneuver into the best positions, which are more likely to be at the forward edge of friendly troops...

Doesn't it then make sense to give them long range capability? As has been seen in combat video, riflemen are going to shoot back at those distant targets, anyway. I doubt that would change, even if your hypothetical, 12-pound, 6.5 Grendel Magnum LMG was developed and fielded.