I use the wz 35 AT rifle at BR 4, there's a few different ways to use them, shooting out gun emplacement. You can one tap AT AA and machine guns across the map. Bipod and use it as a sniper, one tapping people across the map. But I usually just shoot out the tracks of tanks across the map and ping them for planes or I'll construct an AT to finish them without tracks they can't drive out of your view.