I agree with Bigal, that it is too close, but the FAA classifies drones as aircraft. As such, shooting at an aircraft is illegal. People have gone to jail for shooting at drones. Not really the shirt cannon, but a shotgun for sure. I mean if I am flying 100' at 25mph over property, and someone shoots it with a 12g slug, I am 100% reporting that to law enforcement and the FAA. Even just shooting at. I might also be impressed at the shot with a slug...
It is illegal to shoot at aircraft, manned or not. If they wanted to try and sue me or have me arrested for privacy violations, they should contact law enforcement.