.455 in (11.6 mm)
| United Kingdom|
| British Military, North-West Mounted Police, Colonial Military/Police Forces|
The .450 Adams was a British black powder centrefire revolver cartridge, initially used in converted Beaumont–Adams revolvers, in the late 1860s. Officially designated .450 Boxer Mk I, and also known variously as the .450 Revolver, .450 Colt, .450 Short, .450 Corto and .450 Mark III, and in America as the .45 Webley, it was the British Army's first centrefire revolver round.
.450 Adams Wikipedia
The .450 was adopted for the Adams revolver in November 1868, and served until it was replaced in service in 1880 by the .476 Enfield (in the Enfield Mark 1 and 2), which was in turn supplanted by the .455 Webley cartridge in 1887.
Originally loaded with 13 grains (0.84 g) of black powder under a 225-grain (14.6 g) bullet, it was later also offered in a smokeless powder loading. Despite the different designations, the .450 may be fired in any weapon chambered for .455 Webley, .455 Colt, or .476 Enfield.
While not considered a suitable military round, 450 Mark III cartridges did serve in reserve for the British armed forces as late as the First World War. The .450 Adams also proved popular among civilian users of Webley RIC and British Bulldog revolvers, being loaded in Europe, and persisting in the United States until around 1940. Both Colt and Smith & Wesson offered revolvers in .450 Adams.
It was roughly similar in power to the contemporary .38 S&W, .41 Colt, or .44 S&W American.
Handloaded ammunition can be made from shortened .455 Webley brass.