I am not a historian but is it not true that not that many years ago, it WAS very hard to obtain ammunition and components in many Nitro Express chamberings. The reason why the bolt action .458 Win Mag became popular, double rifles with no ammo were extremely cheap and why eventually Bertram started making brass, Woodleigh bullets and Super Simplex reloading equipment to cater for the demand in Australia at least where many of the doubles resided for too short a time.

However if brass could be made and converted from the .405 anyway then ...