Does it use the 460 WTBY case?
If so, what makes it different from the .505 Barnes Supreme?

I did find this"

"Forrest - when I worked at A-Square in the 90s, I built one for myself. Left handed, so was done on a big Sako action.

The big pinch for it now is there is virtually no one making brass, let alone ammo. The Lott, Gibbs, or Jeffrey would be much wiser choices in terms of component availability. One can open up .460 Wby cases, or shorten .500 A-Square cases (which are also rare as hen's teeth), and you could get along fine in the states. However, in order to really use it for it's purpose you would need to commission a special run of properly head-stamped brass to get it into Africa."