Quad-rotor gun

[MA-Caver]

I can see military and LEO tactical applications for this. It may not be "silent" but it would be effective in noisy situations and observations... even hostage situations. Perhaps with a little tweaking they could find a way to quiet the motors down even more.
Either way it's a deadly combination of firepower and (adult) kids toy.

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Not sure what kind of rounds this guy is using, I imagine that the "targets" are rigged to blow when struck.

Also in the wrong hands this could be a devastating piece of equipment and one wonders if it would be "hack-proof".

 

[Bikewr]

Well, these sorts of aircraft are currently being deployed by the military for close-in observation and intelligence gathering. Most of the ones I've seen are smaller and quieter; little more than a kid's toy with an RC control and a camera.
In order to carry a weapon, you need more stuff. Ammo, servo motors, targeting system. So, the rotors have to be bigger (and noisier) and the motors more robust. In this case, it looks like a typical 9mm submachine gun and the targets were indeed rigged with "Tannerite" or something similar.

As you can also see, the aircraft is just about coping with the load it has to carry.... I wouldn't expect much in the way of performance.
However, the potential for a very small, remote-controlled assassination weapon is certainly there....