I think I got it sorted. As Lt. Trey noted, M18 all the way for smokes.
Out of curiosity, is there a preference between vanilla, ACE, and RHS variants of things? I'm thinking of the frags and flashes.
I also could not find any 100 round belt ammo, just pouch variants in the 100 rnd. In-game models seem to look the same between the 100 vs. 200 rnd so perhaps it don't matter.
Cheers,