If you want to inflict maximum damage with mortar or artillery fire, you did to fire them in pistol mode. With mortar it can't be done but India had done the same with arty. But while doing so, the range of any artillery is seriously diminished and you cant fire it at long range. Most of Paki outpost are beyond the reach of direct arty fire.
If you ask about damaging effect of any 80mm mortar shell on a stone bunker, then you should know that any direct hit from one such shell could devastate a reinforced bunker too. Why you think we do use 14mm or 12.7mm AMR against such posts. Look the effect of any 30mm AA gun in any such post.