.455 Webley

The .455 Webley is a rimmed, straight-walled revolver cartridge that armed the British and Commonwealth military service revolvers — most notably the Webley Mk VI and the Enfield No. 2 — from the 1890s through the Second World War. It saw six official marks over that service life, each changing the case length, bullet profile or propellant charge while keeping a common bullet diameter and rim, so that later ammunition would still chamber and fire in earlier revolvers.

The Mk I, adopted in the 1890s, used a longer case loaded with black powder and a heavy round-nose bullet. The Mk II, introduced after cordite propellant let the case shorten considerably, became the standard load for the rest of the cartridge’s service life and is the version this entry’s dimensions describe — later marks (III through VI) changed bullet shape, including a wartime hollow-point Mk III abandoned under the 1899 Hague Declaration and a flat-tip Mk IV and V, without changing the Mk II case that most of them share.

This entry carries the full C.I.P. dimensional standard for the Mk II, the only mark with a free published standard, and one ball load’s bullet mass, converted from a published 265 grains and recorded as estimated. No source states a test barrel length for any published velocity figure, British service or modern commercial, so no velocity is recorded and the cartridge computes no muzzle energy or trajectory.