According To Sharpe:

“The .357 Magnum cartridge was born in my mind several years ago. On a hunting trip with Col. D.B. Wesson, Vice-President of Smith & Wesson, a pair of heavy frame Outdoorsman model revolvers were used with a large assortment of handloads developed and previously tested by myself. In the field they proved entirely practical, but Col. Wesson was not content to attempt the development of a Magnum .38 Special cartridge for ordinary revolvers and set to work on a new gun planned in the field. For more than a year before the release of this gun, Col. Wesson manufactured a few pilot models, building and rebuilding each one, redesigning this and that until he found a suitable combination. I did not design the gun or the cartridge, however a number of my ideas were incorporated in the design of this gun, tested through an understanding of handloading problems, and a number of weak points in ordinary revolvers were quickly corrected.”