John,
I have an entire chapter dedicated to TR and I have done a LOT of research on his use of the .405. However, what most people are not aware of is that TR was not the only, nor the first, hunter to use the .405 in Africa - and I have lots of chapters on famous and notable hunters who used the .405 in Africa, India and North America. Indeed, the more I look the more I find! The one area that I have having trouble finding info, photos or stories, is here in Oz. I believe that some of the Northern Territory buffalo hunters used the .405, although most of them used surplus SMLEs, but I cannot find any actual data on the .405 in Oz!
cheers,
Bob