Lynx,
Thank you so much for the info. It reinforces some of what I have learned. I think Nawab Dowlan's daughter was married to one of the Nizams son's about the same time the gun was delivered in the 30's. Perhaps he used it in some hunting expedition after the marriage ceremonies were completed.
The gun proportedly came out of India thru the Nizam's collection.

I would love to see some good close-ups of the 500/450 from all angles. Is the gun still in use?