OAL and magazines, yes! A different case would be required, along with rifles and other big costs. Then, less ammo could be carried.
So they’re looking more at what can be done with 5.56mm for most soldiers. I can see carrying 14.5” barrels to drive vehicles or clear buildings, but there’s nothing wrong with using a rifle with a 20-inch barrel for the field and getting more intimate with dirt. Might lend to running a little more bullet length, if bullets didn’t get impacted in cases too much in the field (from going in and out of chambers too many times).
Improving on what’s already done can be complicated, eh? ;-)
Ain't that the kick in the pants, though?
The old "cone of fire" concept for the individual rifleman hasn't been around for a long time so far as I know, but then there is more than a little use for suppressive fire, particularly in MOUT operations.
I guess what I'm saying is the real bitch here is that the one round that does everything "enough" without giving up too much of anything in particular seems to be the 5.56.
Oh well....