You can chech the camera variables by selecting the camera, click the rotate drop-down button, then pressing the "x" button above the attachments button.

Proof of concept for camera manual aiming. The gun doesn't fire at angles out of its reach. It follows where your camera is looking at. To edit the traverse angle, edit the max rotation of rotators rotating at Y axis, as well edit their divisor equal to the rotator angle like this input/90 where 90 is the rotator angle and input is the camera input.
You also need to edit the gun activation FT as well.

DGActive & abs(DGYaw) <= 70 & abs(DGPitch) <= 45

where DGActive is the variable whether the camera is active, DGYaw is whether the camera looks left or right, in degrees, DGPitch is whether the camera looks up and down, in degrees, 70 is it max angle before deactivates, and 45 is it's elevation on both directions. Take note the abs() before each camera inputs as it only takes absolute value of camera angle. You can even make different elevation and depression values by specifying the both positive and negative values.

I'm terrible at explaining things, hope you understand XD

Alisuchanka