There’s all kinds of commercial military drones around and they’re obviously far more refined and thought out than this one, but it’s equally crazy/impressive that with todays tehcnology pretty much any individual can just buy a drone and strap an actual rifle to it. Sure, it’s not accurate by any stretch, but if you have few thousand dollars laying around (and a access to firearms) you could to this too.

That would obviously be a Really Bad Idea™ for multiple reasons, but from a purely technical view it’s fairly simple.