.38 S&W [SEP] designer
.38 S&amp;W
The .38 S&W (9×20mmR) is a revolver cartridge developed by Smith & Wesson in 1877. Versions of the cartridge were the standard revolver cartridges of the British military from 1922 until the 1960s. Though similar in name, it is not interchangeable with the later .38 Smith & Wesson Special due to a different case shape and slightly larger bullet diameter.
History.
The round was first introduced in 1877 for use in the S&W .38 Single Action. 
After World War I, the British military sought to
Lancaster pistol
The Lancaster Pistol was a multi-barrelled (either 2 or 4 barrels) handgun produced in England in the mid-late 19th century, chambered in a variety of centrefire pistol calibres—chiefly .38 S&W, .450 Adams, .455 Webley, and .577 inch. The designer, London gunsmith Charles Lancaster, began his career in 1847 as an apprentice to his father, Charles Sr. During the 1850s he invented oval bore rifling and the gas check bullet.
Description.
It was a modernised version of