Model 1913 was the result of years of development in conjunction with the British government. Finally adopted in 1913, as Model 1913 MK1N for Royal Navy issue. Same breech-locking system as Model 1910, but has an external hammer. Chambered for .455 Webley Self-Loading cartridge. About 1,000 Model 1913s were sold commercially and serial-numbered along with smaller-caliber pistols. In 1915, a variation of Model 1913, with butt slotted for a shoulder stock, adjustable rear sight and hammer safety adopted for use by Royal Horse Artillery. Shoulder stocks are very rare. Double values listed for RHA model. All militaries were numbered in their own series; about 10,000 made in both variations.