i work on those cars for a living, and while a bullet might not puncture the thick part, there are PLENTY of tinner areas (venting caps, lines, etc..) that could EASILY be punctured.

not to mention some of those tanks are so old and degraded they have weak spots.

or, hit an air hose and throw the train into emergency braking, possibly derailing it and killing the crew.

you wouldn't shoot at a high way or an airplane runway, why would you make a shot like that?

stupid, thats why