This pistol is actually fired by action of a hammer striking and driving a firing pin into a center-fire cartridge's primer.
The hammer is covered by the rear of the slide.
The "hammerless" designation was merely an advertising designation pointing out the pistol's particular suitability for concealed carry.
Special features include a serrated slide to prevent slippage during manual cycling of the slide and two safety mechanisms (a grip safety and a manual safety).
The grip safety is a spring-loaded piece making up the back strap of the pistol.
The grip safety, though not solely restricted to them, was a typical feature of Colt automatic pistols.
A magazine safety was added on later models; this feature prevents the pistol from being fired with a round in the chamber and the magazine removed.

In 1908, a .380 ACP version of this gun was introduced.
Called the Model 1908, it is nearly identical to the Model 1903 except for the bore diameter and the magazine, which hold seven rounds (one less than the Model 1903).

Grip panels are black checked hard rubber, checked walnut, or special order materials (ivory, mother of pearl, inset medallion).

Sights are fixed, although the rear sight is drift-adjustable for windage.

Metal finish is blued or nickel, and some special-order finishes such as engraved, silver- or gold-plated.
This pistol is actually fired by action of a hammer striking and driving a firing pin into a center-fire cartridge's primer. The hammer is covered by the rear of the slide. The "hammerless" designation was merely an advertising designation pointing out the pistol's particular suitability for concealed carry. Special features include a serrated slide to prevent slippage during manual cycling of the slide and two safety mechanisms (a grip safety and a manual safety). The grip safety is a spring-loaded piece making up the back strap of the pistol. The grip safety, though not solely restricted to them, was a typical feature of Colt automatic pistols. A magazine safety was added on later models; this feature prevents the pistol from being fired with a round in the chamber and the magazine removed.
In 1908, a .380 ACP version of this gun was introduced. Called the Model 1908, it is nearly identical to the Model 1903 except for the bore diameter and the magazine, which hold seven rounds (one less than the Model 1903).
Grip panels are black checked hard rubber, checked walnut, or special order materials (ivory, mother of pearl, inset medallion).
Sights are fixed, although the rear sight is drift-adjustable for windage.
Metal finish is blued or nickel, and some special-order finishes such as engraved, silver- or gold-plated.
Colt Model 1903 Pocket Hammerless