At a glance, this pistol is visually more similar to the later Colt 1911 than to the Colt 1902 Sporting Model from which it evolved, but has a number of differences -- the lack of any safety as well as the lack of a slide lock, the magazine release is at the bottom of the grip rather than a button on the side, and a wedge retaining the slide.
The .38 ACP was a slightly less powerful cartridge than the 9×19mm Parabellum and it is now considered the bare minimum carry caliber for self defense.
[1] The .38 ACP (aka .38 Auto) and the .38 Super use cases with identical dimensions, the only difference being the maximum operating pressures of each.
The first pistols featured the milled pattern similar to the 1902 Sporting Models, but Colt transitioned to rear cut slides around the spring of 1905, apparently for all their automatics.
This would indicate that only about 1,700 or so 1903 Pocket Hammers had the rear milled slides, making them the earliest and hardest to find of the type.
[3] Only a scant handful of 1903 Pocket Hammers were used by the military, and then only as secondary arms purchased not pursuant to contract.
However, the Model did see significant sales in Mexico prior to and possibly during the chaos of the Mexican Revolution (1910–1920) so many of these found their way into military and para-military hands.