Testing, testing...

[stanc]

...a plastic-cased 5.56 with attachable 12 ga grenade launcher (already with plastic cases) may end up being a preferred solution. This could happen in spite of the superiority of the 6-6.5 mm class of bullets and cartridges as a result of "incremental" and "minimum weight" arguments combined.

Didn't Tony post a few weeks ago that the LSAT people had been directed to stop work on 5.56 CL/CT ammo?

As for the 12ga idea, have you ever tried to hit a man-size target at 200-400 yards with a conventional slug? It's difficult enough with a regular shotgun, but likely near impossible with that underbarrel thing they have now.

We already have multiple ammunition types big time in both 5.56 and 7.62. The only remaining step is to allow the bullet weight in belted ammunition to be different than for box magazines.

Joe, the military has always had multiple ammunition types, at least as far back as the .45-70 era. And they've always had a single load standardized for rifle and machine gun. Special purpose rounds have sometimes been employed (for instance, 5.56 Mk262 and Mk318) for rifles, and standard Ball ammo in machine guns, but that's an exception for mission specific requirements.

The Army's SOP was and is one bullet weight for both mag-fed and belt-fed weapons, so any proposal for two different weight Ball projectiles is pretty much a non-starter, doomed to fail.