The Webley Mk IV .38/200 Service Revolver was a British Service Revolver based on the original series of Webley Revolvers produced by Webley & Scott. The Webley Mk IV also, in part, caused a legal dispute between Webley and Enfield after Enfield released the Enfield No. 2 Revolver a few months later (which was a near exact copy of the Webley Mk IV).
The Webley Mk IV began as an intentional re-design of the Webley .455 Revolver to allow the use of a smaller calibre cartridge to be used. The Webley Mk IV is therefore identical in appearance to the original Webley, although it has been slightly scaled down to use the smaller (but just as potent) .38/200 cartridge (based on the .38 S&W). The Webley Mk IV was also based on the Webley Mk III (a .38/200 calibre revolver intended for police use) with most of the internal mechanisms taken from this design.
The Webley Mk IV features a slightly modified (from the original Webley design) extractor system, which had to be modified to remove the smaller cartridges from the slightly smaller cylinder. The barrel is identical to the original Webley Mk VI barrel, with the same rifling pattern (six grooves) and length.
The Webley Mk IV was intended to produce the same results in terms of performance as the original .455 Webleys while firing a smaller calibre cartridge. The .38/200 proved to be the most effective cartridge with the design, becoming the standard issue British sidearm cartridge in 1932, with the cylinder having room to hold six cartridges.
The Webley Mk IV .38/200 Service Revolver was a continuation of the line of Webley revolvers used by the British Army in the 20th century. Webley sent the design to the British Government to be allocated as the official British Service revolver/pistol. However the Government, looking to save money in the aftermath of the Great Depression of 1829, took the plans to the Government run RSAF Enfield and opened up a can of worms.
Enfield No.2 RevolverEdit
The Enfield No. 2 Revolver was a near exact copy of the Webley Mk IV, although there was a change in the internal mechanisms which meant parts could not be interchanged between them. Webley decided to sue the British Government for £2,250 for design costs although the British Government's defence was handled by Enfield whom claimed the Captain H.C. Boys (designer of the Boys' Rifle) had designed the Enfield No. 2.
Eventually the Royal Commission on Awards and Inventors paid Webley £1,250 for the original design. In the mean time both the Webley and the Enfield were used as the standard sidearm of the British Army until the 1960's, as supply shortages meant that the two (being built in large numbers) would remain in service across the Empire and Commonwealth.
The Illustrated Encyclopedia of Firearms - Ian V. Hogg