PDWs...and other small arms.

[stanc]

I much prefer the MP9 as a PDW, regardless of whether it's in 6.5x25 or 9x19, but a 10.5-inch M4 is what I recall the Infantry School commandant said was going to be the Army's near term PDW.

With that in mind, 6.5 Grendel could be used in a PDW, carbine, DMR/light sniper rifle, IAR, and (if suitable links can be designed) belt-fed LMG.