When Smith & Wesson introduced the .357 Magnum cartridge in 1935, it was something of a big deal. The 44-caliber N-Frame had been tasked to chambering the new load, but the company went one step further in making the fit and finish the best they'd ever done.
Elmer Keith and Phil Sharpe put a great deal of work and experimentation on the cartridge, and they saw it pay off. The ad copy spoke of a load capable of defeating body armor and punching through automobile bodies with authority, and its accuracy was universally lauded. Such was the prestige behind the gun itself that it was built to order for customers, who could choose any barrel length, sight picture, trigger type, and point of impact they wanted. The initial guns were packaged with a registration certificate and referred to as Registered Magnums.
The gun was met with immediate acclaim from law enforcement, with the 3 1/2" barreled version being the most popular. The first specimen off the assembly line (now tragically lost) was issued to J. Edgar Hoover, with the subsequent units going to Keith and Sharpe. General Patton carried one for most of his late career.
Initially, the pistol was simply called the .357 Magnum. When Smith & Wesson went to more prosaic model numbers in the late 1950's, it became the Model 27.