Magnum pistols have been a favorite means of killing in games and film for decades. Fallout New Vegas is no exception, and the Mystery Magnum rare weapon is really devastating. Watch this video to learn how to get it from a man in front of Sunset Sarsaparilla.
From the Creator:
Owned by The Lonesome Drifter who is sitting in front of the Sunset Sarsaparilla billboard next to the highway (little east of El Dorado Dry Lake and north of El Dorado Gas & Service). Can be acquired by passing a barter skill check (50 Barter required) when hiring him for the mission Talent Pool, stealing it from him, or killing him.