Adopted in 1894 and almost identical to the Mk I, the Mk II had a hardened removable steel blade that was added at the back of the frame breech.
Also, the hammer was strengthened and the grip was slightly rounded.
(1894 - 1897) The Webley Mk IV was made from 1899 - 1913.
It differs from the Mk III in that the steel was of different quality, the trigger stop was raised and the slots in the cylinder were made wider.
The ratchet teeth of the extractor were case-hardened and the hammer was made lighter.
(1899 - 1913) Adopted in 1915, the Mk VI featured redesigned, more squared grips, a 6 inch (152 mm) barrel and removable front sights.
Mark 6 revolvers were manufactured by Webley & Scott until 1921, later these were manufactured by Royal Small Arms Factory at Enfield Lock until 1926.
Officially rendered obsolete in 1932 with the adoption of the Enfield No.2 .38 caliber revolvers, but widely used by British troops during World War Two.
(1915 - 1932) The original Mk IV was adopted in 1899.
It improved on the Mark III by being made from different steel, with a smaller and lighter hammer and wider cylinder slots.
In 1942 the Mk IV was officially adopted for military service.
It started as a scaled-down version of the .455 Mark VI revolver, but was chambered for .38 S&W cartridge.