Ducks over decoys #2s or 3s. Geese BBs. Never had a chance at sandhill cranes but we shoot tundra swans over field or floating decoys with BBs. Main thing with geese and swans especially is try to shoot to break their neck, i.e. make sure you lead them. A crane or swan can kill a dog and if you wing one they can cover a lot of distance before you catch up to them on foot or by boat. If I were shooting sandhills I would not send a dog until it was stone dead....those beaks are weapons.
