The 9mm Japanese revolver was a cartridge similar to the .38 S&W.These cartridges are not inter changeable.The rim on the 9mm round is much thinner and the chamber pressure is lower than most .38 S&W loads. Here is an original 9mm Japanese revolver round next to two .38 S&W loads, a recent commercial Remington with 145 grain bullet and an older Canadian Dominion Armories military load with 178 grain bullet.[1] This bullet was used in the Japanese Type 26 revolver. The cartridge saw action with the Type 26 in Russo-Japanese War, World War I and World War II.