Gun/Cannon Input Variable
With the recent (1.11) update (and several prior updates as well), most parts now have customizable input variables, allowing them to be triggered or activated by player inputs outside of the standard basic controls. For example, lights can be set to activate based on throttle input or airspeed, rather than only the activation groups.
The one major category of parts that lacks (and needs!) this feature is weaponry. Guns, rocket pods, and cannons can only be fired by specifically the FireGuns or FireWeapons inputs, respectively. While these inputs can also be used to control other parts as described above, it is currently impossible for guns or other weaponry to be triggered by, for example, an activation group or a certain control input. (Missiles are kind of an exception, since they do fire if dropped from a detacher or pylon, though they do not lock onto targets. Bombs just go boom regardless.)
While this may seem like an odd request, adding an adjustable Input variable to the Wing Gun and Minigun part would be a huge improvement, since it could allow for guns to be used for more advanced purposes. For example, one could conceivably create a 100% automatic turret that not only tracks targets (as some already have the capability to do in-game), but automatically opens fire once the target closes to within a certain range.