Are you saying that the low fire rate is a bad thing for an infantry hmg? 12.7mm ammo is quite heavy.
Do we know if the new hmg is for vehicles or infantry?
It is heavy that’s true, yet not really a point in either side. You have to remember that this is still a Machine gun. This isn’t an anti material rifle.
Machine guns are used to pin the enemy down so other weapons can nail them. Mortars and the like.
For infantry faster rate of fire can be a means of survival. In an ambush the more the other guy is pinned the worse off he is. Lightweight HMG like this are ambush weapons. Despite the light weight no infantrymen no matter how Rambo is going to be able to fire it off hand in a manner that outside a Wolf Warrior movie is actually effective. So it has to be set up camouflaged and used from a fixed point.
Mass reduces felt recoil, heavier weapon firing the same ammunition will stay on target better. Heavy barrels flex less than lighter ones and have better performance in heating and cooling. Yet again weight becomes the issue. For an infantry HMG you want the solider to be able to hump it on foot over all kinds of hell. Yet not so light it breaks or is useless as a weapon. This is why the US canceled two attempts at similar the XM806 and XM312. Also why the .338NM MG. It offers a weapon of the same range, similar power and yet is light enough to be fired from the shoulder. Meaning it’s more mobile.