The Colt Model 1908 Pocket Hammerless is a variant introduced five years later in .380 ACP caliber.

The hammer is covered and hidden from view under the rear of the slide, which allows the pistol to be carried in and withdrawn from a pocket quickly and smoothly without snagging.

Bank robber John Dillinger was carrying this model of pistol when he was shot by FBI agents outside the Biograph theater on July 22, 1934, and another famous bank robber, Willie Sutton, had one when he was captured by police in Brooklyn on February 18, 1952.

The FN Model 1903 pistol design is related to the Colt Pocket Hammerless, but it is physically larger due to its chambering in the 9×20mm SR Browning Long cartridge.

[3] In October of 1944, the design was modified with the addition of enlarged sights, an increase in the number of slide serrations from 17 to 19, allowing 1911 tooling to be used.

[3] Former Japanese Prime Minister Hideki Tojo used a Colt Model 1903 to attempt suicide shortly before his arrest for war crimes on September 11, 1945.

The Colt Model 1903 Pocket Hammerless was used in the assassination of SS-Obergruppenführer Reinhard Heydrich (top Nazi officer) in the Protectorate of Bohemia and Moravia on May 27, 1942, in Prague.

In Warlord Era China, some cottage artisans created pistols that were visually similar to the Colt Model 1903, but dissimilar in mechanics (such as the lack of a grip safety and a heel magazine release).

[6] It was the pistol of choice for Raymond Westerling, a captain in the Royal Netherlands East Indies Army.