RE: 12G / 00 Buckshot / Drop
You will never know until you shoot YOUR gun with that load. That will tell you where to aim at what distance and what sort of pattern you will get. You could probably extend your range a bit beyond 30 yards though with a full choke, shoot it and see. 40 or so is probably pretty doable but anything beyond 50 with buck shot is just reckless in my opinion. If you are going to shoot that far just use slugs.
Paul