The 44 S&W Special was introduced with the introduction of the Triple Lock( 44 Hand Ejector, New Century).I believe they were also available in limited numbers of 38-40, 44-40, and 45Colt. The .455 production was for WW1 British contract, some of which were re-imported and converted to 45 Colt. The design was modified at the request of Brits. to delete triple lock feature, to save cost ( and maybe improve reliability in trenches).
Mike