.455 Webley is a British handgun cartridge, most commonly used in the Webley top break revolvers Marks I through VI. It is also known as ".455 Eley" and ".455 Colt". The .455 cartridge was a service revolver cartridge, featuring a rimmed cartridge firing a .45-caliber bullet at the relatively low velocity of 650 ft/s (190 m/s). The result was a cartridge and handgun combination with comparatively mild recoil. The .455 MK III "cupped" cartridge was rated superior to the .45 Colt in stopping power in the disputed United States Thompson-LaGarde Tests of 1904 that resulted in the adoption by the U.S. of the .45 ACP cartridge. The .455 Webley cartridge remained in service with British and Commonwealth forces until the end of the Second World War. Variants Six main types of .455 ammunition were produced: .455 Webley Mk I [11.55×21.7mmR]: Introduced in 1891. 265 grain (17.2 g) solid lead round-nosed bullet propelled by black powder. All subsequent .455 designs used cordite propellant. In 1894 some Mark I cartridges were loaded with cordite (identified by a case cannelure and "C" headstamp) but it was found combustion was more efficient in a shorter case. .455 Webley Mk II [11.55×19.3mmR]: Introduced in 1897. 265 grain (17.2 g) solid lead round-nosed bullet propelled by cordite. With the change to cordite propellant, case lengths were reduced. There are minor differences between the Mk I and II bullet shape, though these concern the internal dimensions and so are not immediately apparent. (1900-1912) Replaced the Mk III until it was replaced by the Mk IV. The bullet is made of a 12:1 ratio lead-tin alloy. (1914-1939) Replaced the Mk V until it was replaced by the Mk VI. The bullet is made of a 99% lead and 1% antimony alloy. .455 Webley Mk III [11.55×19.3mmR]: Introduced in 1898. The famous "Manstopper" bullet intended for police, civilian and colonial use. Essentially, the Mk III was a 218 grain lead "hollowpoint" design, propelled by cordite. The cylindrical bullet had hemispherical hollows at each end—one to seal the barrel, the other to deform on impact. This bullet was soon prohibited for use by the military because it was not compliant with the Hague Convention of 1899. The Mark III was withdrawn from service in 1900 and the Mark II was reintroduced. .455 Webley Mk IV [11.55×19.3mmR]: Introduced in 1912. 220 grain, flat-nosed wadcutter with cordite propellant. Designed with the goal