If you took a chicken, crossed it with an ostrich, bulked it up to 500
pounds, stretched it out to roughly 11 feet, put a bony crest on its
head (like some ancient Greek helmet), added a dinosaur tail and a pair
of forelimbs with five-inch claws, and then, finally, stuck some
feathers on it ... you would have what paleontologist formally calls Anzu wyliei.
Depending on range, I'm thinking 12-gauge magnum buckshot or something in a nice .30-caliber.