New Army "Caliber Configuration Study"

[stanc]

The problem is not so much the gun but the weight of ammo. 7.62x51 MG ammo is already considered undesirably heavy for man-packing, but .338 ammo weighs about twice as much. That's the main reason why any MG in this class is highly unlikely to be routinely carried on foot patrol, but will be held back in the fire support role, to be brought out when really needed.

How do you expect it to be brought into action "when really needed" if it isn't with the patrolling unit???

The greater cartridge weight only means that fewer rounds could be carried by the patrol. It should be fairly obvious that if a 27-lb M240B and (for example) 1200 rounds of 7.62 ammo can be carried on patrol, it would be just as easy to carry a 24-lb LWMMG and 650 rounds of .338 ammo.