Many things changed with the development and introduction of the .357 Mag, both gun and cartridge, in 1935. For the first time, a shooter could buy a powerful revolver that accurately delivered heavy bullets at high velocities. Following that introduction, the outdoor magazines were full of stories of how the new magnum was used on everything from jaguar to caribou. Somewhat more ominously, we also heard how agents of the FBI were using the guns in their ongoing struggles against gangsters of various stripes.
Seldom has any gun or caliber so quickly achieved a reputation for performance and quality, as did the original .357 Mags. It would have continued to sell as the US economy recovered from the Depression in the late 1930s, but World War II came along in 1941 and the American gun industry turned to military matters.