gun-range

-optimal : the maximum range you have 100% chance of hitting a stationary target (if you don't move either).

-Falloff : after optimal + falloff, you will have 50% chance to hit a stationary tartget.
after optimal + 2x falloff, you won't hit targets (ot just a 1% lucky hit).

-Tracking : this is the maximum angular velocity your guns can follow.
Here begins geometry calculations... there is a tracking calculator and tutorial in the player guide (look left the menu)

All values are properly explained in the tracking guide.