I would take the directed EW Jammer/spoofing approach using directional YAGI antenna.
Anti Drone Guided Missiles would be a little more difficult to develop but not impossible using generic WiFi wireless control.
Gun fire using shot guns against high speed drones isn't very effective
Auchterhouse Country Sports nearby used to hold drone shooting events launching their own RC drones.. A Bren Gun mount will be more effective if a Bren gun was available.
https://www.youtube.com/watch?feature=player_detailpage&v=sNbfEXtngXw#t=507Night time Drone and black Helicopter detection using a P8079HP tube and some C mount CCTV lenses can be made quiet cheaply.
https://www.youtube.com/watch?v=M1D-iTY2kAE