These days it's a little unsettling to see a firearm with a canteen attached, particularly because it's probably safe to assume it was rarely filled with just water. But back in 1862 when this Colt Navy 4-Screw Revolver was originally manufactured, carrying a gun everywhere you went was commonplace, and a built-in flask just made sense.
This particularly rare model was just sold at auction for $14,000. And besides providing refreshment and keeping its owner safe, when full the generously-sized canteen probably also helped to steady the pistol improving its accuracy. On the flip side, when emptied it's safe to assume the impaired marksman's accuracy was terrible at best, and downright dangerous to others at worst. [iCollector via Pocket Pistols, Historic Firearms, & Curiosities via Neatorama]