I can tell you that in many areas of the country including the pro gun states that firing a gun without a valid cause can wind you up in jail in fact you can't even fire a warning shot.
Many areas yes. Not most. But not true of a warning shot. That comes under self defense. In Moreno Valley I see it is possible to legally fire a firearm if not within one half mile from a house, road, or other public property. California state law further says you cannot fire from or at a vehicle. State law which may overrule local law allows the possible use of a warning shot or even shooting of a trespasser if the use of force is deemed appropriate, so you might be able to shoot down a drone where you live. If you have a good lawyer that is.