This question applies to either OSRIC or to AD&D 1st Ed.
A human fighter with strength of 17 has selected “grenade-like weapons” as one of his weapon proficiencies. He carries a small bag with half a dozen mostly spherical baseball sized rocks for throwing at enemies.
He throws a rock at an ogre and scores a hit (not a critical hit or anything, just a normal hit).
How should the damage be calculated?