The Colt 1903 Pocket Hammerless was a very popular pistol for civilians - it was compact, comfortable, reliable, and exceptionally modern for its day. The initial production was all in .32ACP, but 5 years after it was introduced a variant in .380 caliber was introduced - the model 1908 Pocket Hammerless. By the end of World War II, more than 570,000 1903s and 138,000 1908s had been manufactured.

More than a few corporate and government organizations adopted the Colt Pocket Hammerless, among them the Shanghai Municipal Police. This department was led at the time by an Englishman named William Fairbairn, who was an extremely influential developer of combat tactics. His work would prove to be a fundamental foundation for modern police organizations and military Special Forces (he was one of the men primarily responsibly for training WWII Allied special units, including the OSS).