As the title suggest, improve the usefulness of artillery by increasing the range to 8. This still leaves it vulnerable to the missile silo, sniper tower, and defending troops but allows it to take out any other building without being in its range.
This absolutely needs to happen.
rifleman and infantry need to have increased range as well especially rifleman.
The heavy infantry have APCs would be awesome if higher aged rifleman had the sneak ability to help their low stats balance.