Depends on how high the drone is. Public airspace doesn’t start at the ground. I work for a security company. We started selling anti-drone security. This wouldn’t be a cost efficient method for the problem stated. If it was my land or leased land I would have no problem using a shotgun on one. Pretty safe to say if you hit it in a shotgun blast, it’s trespassing.
Pretty safe to say if you hit it in the air with a shotgun blast, you’ve committed a felony no matter how high or low it was. The FAA might not look upon it too kindly.