The use of MGs have been used for range finding. By applying this technique for the game, you can actually improve your hitting %. This is a fun way of playing the game. Here is a quote about the use of this technique, and the site.
"The Chieftain solved the problem of ranging the main gun by using a ranging machine gun with similar ballistic characteristics as the cannon. When the machine gun rounds hit the target, the gunner could be reasonably assured that his cannon round will hit."
http://www.globalsecurity.org/milita.../chieftain.htm