The revolver that shot Wild West legend Billy the Kid was auctioned in Los Angeles for $ 6.03 million.
In advance, the value of the Colt single-action revolver was estimated at two to three million dollars, said the auction house Bonhams.
There was a "lively bidding" on Friday online, by telephone and in the hall.
The revolver belonged to Sheriff Pat Garrett, who shot Billy the Kid on July 14, 1881 in New Mexico.
"It is a relic of one of the most important and well-known stories from the Wild West," explained the Bonhams auction house.
The weapon is in "very good" condition and has a "worn handle".
Record price for firearms
Six million dollars, the equivalent of 5.1 million euros, has never been paid for a firearm anywhere in the world.
The previous record price of 1.98 million dollars was achieved by two pistols from the 18th century that George Washington received as a gift during the American Revolution.
They were auctioned off by Christie's auction house in 2002.
Gunslinger Billy The Kid, who was born Henry McCarty and also called himself William Bonney, died at the age of 21.
While fleeing from his execution, he was shot dead by Sheriff Pat Garrett.
Billy The Kid still has a loyal fan base in the United States who sees him as a kind of Robin Hood of the Wild West.
His life was the subject of dozens of books and films.
The trigger-happy gunslinger is said to have murdered at least four people, but probably more.
Some historians attribute 21 murders to him.