On map MLRS with big caliber -- Rate of Fire = 4 - 6 and no smoke?!

[Imp]

All do produce smoke on firing, may not if you try firing it with only a couple of shots in the tubes.

MLRS MARS ROF 6 so shoot off the whole load in one go (2 banks of 6 shots)
Uragan ROF 4 so shoots half its load in one shot & produces smoke in its hex, needs ROF of 8 to shoot them all at once. (2 banks of 8 shots)