Every single time the subject of drones comes up on FR, the blowhards come out with their “I’d shoot ‘em down!” comments.
Yet here is a proven drone invasion, not just one but dozens of them, big ones! Night after night, with no attempt to hide - in a part of the country where everyone owns guns, het not one was shot down.
Even before I read your post, I was thinking that what is needed against drone swarms, is an M61 Vulcan type system, converted to fire 12Ga Shotgun shells. The overall dimensions of the cartridges are fairly close. Rimmed vs. rimless, and pointed vs. flat nose might be problematic.