Many players might have this issue: when using vehicles with secondary weapon - like Mammy, Apache and Gun turret, you always need to pay close attention to the secondary weapon reloading. And instead of focus on the target, I often more focused on the reloading bar so I can know when to fire the missiles.
It would be much better to add a "reload-complete" sound, to indicate the secondary weapon is reloaded. Or maybe add a reload indicator on the cursor?