When you are attempting to destroy vehicles, pillboxes or artillery, an excellent way to do so is to have a pig with a flamethrower (Pyrotechnics have them, level 3 heavy weapons soldiers, or they can be used in multiplayer mode). Walk it up close to the intended target. Face the target, and let rip with the flamethrower, so all the flames hit the vehicle, pillbox or artillery. It should suffer about 102 to 108 points of damage.