Anyone heard of, or have any experience with this one? I know a guy that owns one of these? the way I understand it, Barnes started it and called it the .505 barnes supreme, A square took it over and did some minor changes to the shoulder and called it the .500 A Square. This is the story I got from the owner of the gun. His gun started life as a .460 weatherby and he had it rechambered to the .505 barnes supreme.