I know the gunsmith who did the 9.3 based on the 416 Rigby. In fact, I have fired the rifle although it is ported so I cannot say what the recoil would be like without it.
FMI go to Cartridges of the World, 10th ED. and find it in the Wildcat section. Another poster on this forum once pointed out that 9.3 mm projectiles were not made to go that fast, but with premiums I suspect they hold up just fine. Our friend hunted the rifle on PG in 2001 with good results. I think his only complaint is the weight of the rifle he built is a bit too heavy but he can certainly discuss specifics with you if he sees this post.
