Double-barreled sawed-off shotgun in Doom style. Anyway you may not have enough time to fire more, and save quite a bit on weight and maneuverability. Maybe some special longer shells with more pellets, any slight touch and those lightweight plastics break and drone goes down.
There are issues though. Skeet guns are 28-34" barrels which is super-long. These guns are also heavy. Once you have ammo loaded up, you're talking 11+ pounds. These guns size and weight make them almost unusable for anything outside of drones. Carrying around an extra gun and heavy ammo is a big commitment both physically and logistically.