Smith and Wesson Model 19

The Smith & Wesson Model 19, also known as the M19 was the world's premiere combat revolver.

History
It was developed on November 15th, 1955 and produced around 1957, with retired U.S. Border Patrol Assistant Chief Inspection Patrol Bill Jordan contributing to the design. However, its ammo predated it to about the 1930s, when police wanted to develop a powerful ammo.

During the events of the Peace Walker Incident in 1974, Big Boss and his mercenary group, the Militaires Sans Frontieres, procured design specs for the Model 19 after doing a training excercise at the Miners' Residence of the Mine Base. The MSF, via their R&D Team, later made improvements to the gun by giving it a longer barrel to increase accuracy, and later by adding a laser sight.

In-game descriptions
"The world's premiere combat revolver, a product of the U.S.A. It combines smooth action with high precision and dependability, earning it a large fan base among combat shooters. (Rank 3) The M19 uses powerful .357 Magnum rounds, which makes for high recoil but gives it enough force to knock enemies off their feet. (Ranks 4-5) The M19 uses powerful .357 Magnum rounds, which means high recoil but enough force to knock enemies off their feet. (Rank 4) The barrel has been extended for improved accuracy. (Rank 5) The addition of a laser sight allows for easier targeting."

- M19 description from Metal Gear Solid: Peace Walker