.455 Webley is a British

United Kingdom

The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 handgun

Handgun

A handgun is a firearm designed to be held and operated by one hand. This characteristic differentiates handguns as a general class of firearms from long guns such as rifles and shotguns ....

 cartridge

Cartridge (firearms)

A cartridge, also called a round, packages the bullet, gunpowder and primer into a single metallic case precisely made to fit the firing chamber of a firearm. The primer is a small charge of impact-sensitive chemical that may be located at the center of the case head or at its rim . Electrically...

, most commonly used in the Webley top break revolvers

Webley Revolver

The Webley Revolver was, in various marks, the standard issue service pistol for the armed forces of the United Kingdom, the British Empire, and the Commonwealths from 1887 until 1963.The Webley is a top-break revolver with automatic extraction...

 Marks I through VI.

The .455 cartridge was a service revolver cartridge, featuring a rimmed cartridge firing a .45 bullet

Bullet

A bullet is a projectile propelled by a firearm, sling, or air gun. Bullets do not normally contain explosives, but damage the intended target by impact and penetration...

 at the relatively low velocity of 650 ft/s (190 m/s). The result was a cartridge and handgun combination with relatively mild recoil, but with good penetration and excellent stopping power

Stopping power

Stopping power is a colloquial term used to describe the ability of a firearm or other weapon to cause a penetrating ballistic injury to a target, human or animal, sufficient to incapacitate the target where it stands....

. It was rated superior to the .45 Colt

.45 Colt

The .45 Colt cartridge is a handgun cartridge dating to 1872. It began as a black powder revolver round developed for the Colt Single Action Army revolver, but is offered as a magnum level handgun hunting round in modern usage. This cartridge was adopted by the U.S. Army in 1873 and served as the...

 in stopping power in the disputed United States Thompson-LaGarde Tests

Thompson-LaGarde Tests

The Thompson-LaGarde Tests were a series of tests conducted in 1904 to determine which caliber should be used in new military handguns. The US Army's fighting men had considerable difficulty stopping the Moro warriors and other combatants with the .38 Long Colt, and the Army began to consider the...

 of 1904 that resulted in the adoption by the U.S.