You suggest:
Quote Originally Posted by Compost View Post
The .338 is a good cartridge ' for a sniper’s bolt-action rifle ' but I think a bad compromise between 7.62 and 12.7 ' for use in any MG ' ...
I disagree, it's not much if any better as a sniper round than the .300 and 7 to 8mm Magnums plus it carries a weight penalty and thus concomitant weapon weight impact. It also is 'overkill' for many tactical sniping applications. It was developed as a military cartridge by the Finns who can make good use of it; it was adopted by others simply because it was available and a moderately good solution to lessening the load of the .50 as a long range man stopper (a purpose for which said .50 is also not particularly suited...). The .338 cartridge may with further development improve to the point that it is a good -- as opposed to adequate -- sniper round but it's not quite there yet IMO -- and weapons that use it will need to be lightened which will require some sort of recoil attenuation. It's IMO a niche weapon which has achieved the success it has simply due to adequacy (as opposed to goodness or excellence), availability and being non-American (not that there's anything wrong with that...).
There is one point of contention, that 10mm for pistol and SMG. 10mm might be preferred in the USA but many in NATO and affiliates would propose ' 9mm with alternate barrels for 6.5mm '.
True I suppose -- the issue is whether one wants a usually man stopping cartridge or a usually lightly wounding, rarely man stopping cartridge. What a difference a mere millimeter (and about double the amount of gunpowder / propellant and another gram of bullet weight) can wreak...

The issue you raise is one of cost and habit, not of effectiveness. It's certainly valid and such a change may not be totally cost effective but this is all conjecture anyway.
But none of this throws light on what the usually astute GD really intends for its LWMMG.
Uhh -- to sell it to anyone who thinks it might be useful for their purposes? Or who just think it's a neat weapon or toy? GD is not into tactical or operational panning and effort, just into making things that will or certainly might sell. GD has indeed generally been astute and their small arms / weapons operations particularly so -- except for the Saco M60 projects (and those were not totally Sacos or GDs fault...).

Military forces should not focus on Afghanistan in determining their future equipment buys but history indicates many surely will. GD likely is quite aware of that propensity...