I'm no expert but did any company make the 505 as a general production chambering? From what I have read very few were made on special order by the various companies in the US, Britain and Europe. CZ now makes it's 550 in the caliber though there have been mixed reviews of them by people who have bought them as you would undoubtedly have seen on these forums.

Thanks for posting some very interesting questions. I hope that someone who knows this well would post answers.

Good hunting!