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

[stanc]

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.

Of course. It seems likely that such a cartridge -- and magazines for it -- would necessarily have more volume than even 7.62x51.

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.

No doubt. For that matter, I wouldn't be surprised if it suffered the same fate as its predecessor, the Interim Combat Service Rifle.