The British dropped the .455 cartridge in the early 1930s for its revolvers as it was felt that the recoil of the large round made it difficult to train soldiers in accurate revolver fire. They replaced it with a new cartridge known as the ‘Cartridge S.A. Ball Revolver .380 inch Mark 1’ in November 1930. This round had a lead bullet but concern about the legality of lead bullets led to the adoption of a jacketed round in 1937. This was the Mk IIz round and was in service at the start of World War II. the round consisted of a brass case with a rim to it and a blunted round nose bullet with a cupro nickel or gilding metal envelope and a lead/antimony core.
The weight of the bullet was 178 grains and the propellant was either four grains of cordite or 3 grains of nitrocellulose which gave a muzzle velocity of 600fps and a chamber pressure of 8 tsi.
The headstamps on the base of these rounds show they were made in 1942 by Royal Laboratories:
These rounds were usually issued in small cardboard boxes with twelve rounds in them. As the service revolvers in use during World War II held six rounds this allowed two full cylinders:
The round was consistently criticised for being underpowered, however this is probably because officers were used to the old man stopper cartridge. For the ranges and use most revolvers were fired at the round was perfectluy adequate and it was far easier to train men under wartime conditions on the lower powered rounds than the old .455 cartridges.