Left hand radical - the side-form of
手. The indexing element. The action of pounding, beating, or hulling is plainly hand-and-arm work, often gripping a pestle and driving it down into a mortar. Puts
捣 in the action-of-the-hand family with
打 (hit),
撞 (collide),
砸 (smash),
敲 (knock).
