If the little drones are driven by people that know what they are doing, even an experienced shot gunner would have trouble hitting such a small target that moves quickly with sudden direction changes. A semi auto with a lot of bird shot might get it done. I hope to never be on the receiving end of a drone swarm.
There used to be this "gun" show on Discovery channel called "Sons of Guns". It was a father/daughter and staff running a gun shop in Baton Rouge. I won't elaborate on the show's demise but some of the episodes were entertaining. In one episode, they equipped a commercial drone with a pistol that fired downwards. This was like 15yrs ago so I'd bet the "cargo" carrying capability of them is much greater now.
PS: in related gun show news, I've been watching an episode or two of History's "Top Shot" before bed. I have the first 4 seasons on DVD although if you are a History channel subscriber you can watch On-Demand for free (with commercials). I am about ready to start season 4, there are 5 seasons. I still need to pick up season 5 on DVD although I might "bite the bullet" and just watch it on-demand...