Will

It is a 9.3x74R. Made by the head gunmaker of Francotte as his personnel rifle in 1935. Despite Cartridges of the World etc. it is not almost a 375, closer to a 35 Whelan, but it is more than sufficient for anything except Buffalo, Ele and Hippo. For those animals there are better options available.

I don't like the idea of a rimless, higher pressure case in a Double. I know that it is done but there is too much that can go wrong with a rimless case. Sort of like a rimmed case in a bolt rifle. You can build a 450#2 in a bolt but it is not really the type of cartridge you would want to use for a variety of reasons including feeding and extraction.

While steel has improved in the last 100 years the design has remained the same and it is not a design for high pressure cartridges. I don't think it would fail but come off the face faster and require constant attention for fit. Those dinky little extractors are not for piece of mind either. Murphy's Law and all that.