The metal casing on the tank of a fuel tanker truck is far too strong and thick to be penetrated by a shotgun blast; it might be able to be penetrated by a bullet from a high powered rifle, but not a shotgun. Also, even if buckshot, or a bullet, penetrated the tank it would not cause it to explode. Bullets are made out of a copper jacket and a lead core and the pellets from a shotgun are either made from lead or stainless steel, none of which create sparks. One of the biggest mistakes made in movie and television is that bullets always make sparks; they very rarely, if ever, do so. Shooting a gas tank (whether it's gasoline, diesel or propane) will not make it blow up.