"Fast ball special".

[Esoomian]

Given that a club is Strength + 1D I'd say a thrown grenade or rock could only be a round Stregnth +1

Better off just letting it explode as if you hit someone hard enough for the impact damage to hurt them and it may very well bounce back before it gets to explode.
_________________
Don't waste money on expensive binoculars.

Simply stand closer to the object you wish to view.