Any idea how far you have to lead a drone?
The depends on a huge number of factors, mainly the altitude, speed, and what type of weapon you are using.
If using a long-range duck hunting shotgun with a severe choke, the lead distance would be much greater than if using a fast-moving 5.56 round from an AR.
Here are some guys practicing drone take-down on a ranch in Texas...
http://www.youtube.com/watch?v=nGgEFOD8JloFor the little drones that will sniff for chemicals around your windows, the weapon would need to be something like a fire extinguisher that would not impact your neighbors' houses.