Loren's brute force can be your solution to your problem as it would allow easy "Intelligence adjustments" by adding more iterations. In a real situation all these factors would be handled either with formulas or simply brute-force simulation:
Fire an electronic shell.
Apply all the relevant forces and see where it lands.
Adjust it and try again until the electronic shell hits the target.
Now you have your numbers to send to the gun.
A difference between artillery games and real artillery situations is that all sides have 100% information and that there are typically more than 2 opponents.
As a result, your evaluation function should consider which opponent it would be more urgent to try and eliminate. For example, if I have an easy kill at 90%, but a 50% chance on someone who's trying to kill me and just missed two shots near me, it's more important to deal with that chance.
I think you would need some way of evaluating the risk everyone poses to you in terms of ammunition, location, activity, past history, etc.
For more information you can refer the following link:
STEPS TOWARD BUILDING A GOOD AI FOR COMPLEX WARGAME-TYPE SIMULATION GAMES
For the best of career growth, check out Artificial Intelligence Online Course and get certified!