Up close with some incestment it 1-shot CWs even on legend without using double-shotted. But anyway, yes, it totally should go through shield of 1 shieldvermin, penetrate him and them hit another Stormvermin, but now for less damage than if it penetrated normal stormvermin first. So a shot is not blocked, byt it can no longer deliverr its full potential to otther targets.