These would not have lit off a fuel tank, the bullet would have entered the tank and gone out immediately. This has been tested in the past even with 3.5 rocket rounds, even the 3.5 rounds with explosive heads enter into the large tanks and get snuffed out. Fuel like this need lots of air to ignite as a flame, or what may look like an explosion, and where one gallon of gas has the potential energy of up to 40 sticks of dynamite. You have to get lots of air into it, and then to become a mechanical explosion the fuel would have to be confined in some what, which is why fuel is not considered a great explosive, it needs lot of air and needs to be confined, very had to get it just right.
from CTI Consulting http://ift.tt/2y97Q3G