Staff Writer (Updated: 9/27/2016):
The Model 1903 made use of a single-action blowback firing action. It utilized .32 ACP caliber ammunition in an 8-round detachable box magazine. Weight was 33 ounces while the length measured in at 205mm with 127mm of this dedicated to the barrel. The gun was given a manual safety as well as a grip safety. Sites consisted of a fixed front and a rear adjustable.
The Colt Model 1908 Pocket Hammerless became a variant of the Model 1903 and appeared beginning in 1908. The new model chambered the .380 ACP cartridge. The .380 ACP cartridge was a rimless cartridge design also from John Browning with production beginning in 1908 under the Colt Manufacturing Company brand. The Model 1908 made use of a 7-round detachable box magazine, this being one of the major variations between the M1903 and the M1908, while the new pistol also sported a different bore diameter.
Production of the M1903 and M1908 pistols ran until 1945 to which some 570,000 examples were placed into circulation. US General George S. Patton kept a Model 1908 - one of the many American wartime heroes of World War 2 - appropriately starred with his current rank along the grip.
Despite the name of Pocket "Hammerless" assigned to the series, the M1903 and M1908 both indeed made use of a hammer in their function. The hammer was unseen, however, as it lay under the slide component.