I think the dummy that places the machinegun might be inverted... Try opening SU-14's model (CP3-Main\units\mechanical\custom\SU-14\) with java 4d editor (http://panzers.ucoz.com/load/jre_stormregion_4d_editor_v01/8-1-0-37), finding the dummy (should be named gun2m0 or sth like that, you'll see, it will be the one placed at the end of the MG) and turning it by 180 degrees.
(Sorry, I have seen that there is a machine gun also back the tank!!! wooow xD) But why this machine gun shoot also if the enemy is in front of the tank??? biggrin
The first problem is a my error :P but there is another problem! " this machine gun shoot also if the enemy is in front of the tank???"