The Grille's got 12 HE rounds, so that's enough for two fire missions.
One fire mission, depending on the crew skill (affects reload time) takes about 3 minutes and 20 seconds to complete. There is also no target reference point left to mark the last FM like mortars do (dunno why), so you are wasting one round (spotting) per fire mission.
I'll probably see, if I can clone the Grille and make a new unit and call it "Grille (indirect)" or something and add 1-2 of those per BGs that already the direct-fire Grilles.
