.50 Handgun (Desert Eagle Mark XIX), is the .357 Magnum variant, noted by its fluted barrel and 9-round capacity. The gun operates in DAO (instead of the correct SA) and the slide locks back automatically when a reload is initiated. The pistol fires continuously if the fire key is held.
The game takes place in the 1960s, which makes the Desert Eagle highly anachronistic: the Mark I variant was not introduced until 1982, and the Mark XIX was not developed until 1995.
Desert Eagle Mark XIX on Wikipedia