The .357 Magnum is the oldest handgun "magnum" cartridge. Smith & Wesson played a major part in the development and success of the cartridge and revolver that went with it. Firearms writer and experimenter Philip Sharpe is credited for its development during the 1930s when police agencies were asking for a more powerful round. S&W's Dan Wesson agreed to produce a new revolver that would handle "high-intensity" .38 Special loads, but only if Winchester would develop a new cartridge. Winchester introduced the .357 Magnum, which was dimensionally identical to the .38 Special except for a .125 inch longer case, and the first revolvers (referred to as ".357 Magnum Models") were completed by S&W on April 8, 1935.
Retired Assistant Chief Patrol Inspector of the U.S. Border Patrol, famous gun fighter, and noted firearms and shooting skills writer Bill Jordan consulted with Smith & Wesson on the design and characteristics of the Model 19. Jordan's idea for a "peace officer's dream" sidearm was a heavy-barreled four-inch K-Frame .357 Magnum with a shrouded barrel like the big N-frame .357 and adjustable sights. After a year of experimentation with improved-strength steels and special heat-treat processes, the result was the .357 Combat Magnum (later designated Model 19), with the first serial-number gun (K260,000) presented to Jordan on November 15, 1955.