[Visual77]

It could be that m_itemCount or the spawner_grab event isn't working on the grenade launcher, I'll check later.
Edit: What custom map is that btw?

I think the solution could be to check for m_itemCount 1 or 0. GetEntProp(entity, Prop_Data, "m_itemCount") <= 1)
But I'd like to try on a map that has the grenade_launcher_spawn.