I second Neal in saying Welcome
I had a thought about drivetrains.
The drivetrain usually includes the gearboxes AS WELL AS the suspension and tracks. an idea is to make different kinds of tracks (for instance, smoother tracks work better in urban areas and not as well in other locations) or certain improvements to the gearbox, better suspension to improve stability (which means a lot when you are trying to aim the gun)
I'm not a tank expert (Not entirely anyways) but I know that you really can't improve a tank in the field, but you can keep it running smoothly and that is the best you can hope for. So perhaps an idea would be to add in a maintenance option to keep everything running in top shape.
But about ammo, I have read stories from german tank commanders who were greeted with nothing more than a loud BANG when a high explosive round hit their tank. I don't know much about Armor Piercing rounds but the way to go would be to "destroy" or "kill" (if said round lands near a crewmember) whatever the round hits.
Just a few thoughts
