WHILE DRILLING ROOF BOLT HOLE, BOOM EXTENDED TO LIMIT, DRILL HEAD WAS LOWERED TO PLACE BOLT WRENCH SO DRILL STEEL COULD BE PUSHED TO CORRECT DEPTH. INITIALLY DRILL STEEL WAS STUCK IN HOLE BUT WHEN EMPLOYEE WENT TO PLACE BOLT WRENCH IN CHUCKDRILL STEEL CAME LOOSE, STRIKING HIS HAND.