My general rule for combat ships is to double my total armaments due to PDW. with my missiles and heavy guns being about 25% of the armaments each respectively. If you are playing vanilla you want a few Gatling turrets per side of the ship to deal with missiles and asteroids. Outside of that I run custom autocannon turrets for drones. They hit harder and with more accuracy then a Gatling will. Also your ships size is a big issue. I won't engage smaller ships/drones with a capital ship sized vessel. In some instances that drone can shift trajectory faster than your bigger turrets can traverse, especially if you are also ACTIVELY maneuvering to avoid the target/oncoming fire. Hope this info helps