Tactical Life posts that the military is changing to the 6.8 in SAW and M4

[Double Naught Spy]

IIRC, in (at least) one of the articles it was stated that they are planning on the same basic ammo load.

Then they aren't actually saving space or weight, sort of getting back to what LRRPF52 was getting at above. Space (volume) is a real issue. Generally speaking, the increase of bulk tends be detrimental elsewhere in ability.

It will be interesting to see if that actually sticks or not. Like so many aspects, this program is going to undergo numerous modifications (which have apparently already started) that compromise intended goals in order to bring it to fruition.