In the years immediately following World War II, experimenters had been developing ever more powerful loads for the .44 Spl. cartridge. It was natural that a more powerful counterpart to that round should be developed in the same way that the .357 Mag. evolved from the .38 Spl.
Out of production and somewhat obscure, the Smith & Wesson Model 29 was once well known only to serious big-bore handgunners. Then in 1971, it became one of the most famous and desirable handguns of all time. Do you know why? Well, do ya?