The guide I have describes how agent accuracy works but not ship based weapons. The targeting equipment has a number but I don't know if it's directly adding to accuracy or if it's a more complicated calculation.

I don't use them much myself except as a gap filler.

 

However, I assume vehicle accuracy works the same way it did in UFO/TFTD. Vehicles don't have their own accuracy stats of their own, so we can assume the vehicle's accuracy is 100%. Therefore the only accuracy levels we can go by is the weapon accuracies.

 

Say the minigun does 10% per shot. Adding a small accuracy mod (+10%) will increase it to 11%. That means each shot on a stationary target will be 1% better.

 

The mods only influence non-rocket projectiles. Rockets home in on their target so they don't work on the launcher's accuracy.

 

- NKF