In the 1870s, Colt needed a double-action revolver design to compete with many ... while the Thunderer and Rainmaker were chambered in .41 Colt and .32 Colt, respectively.

1825 ca. - Percussion-cap guns are in general use. 1830 - The back action lock appears. 1835 - The first Colt revolver. Samuel Colt developed the first mass-produced, multi-shot, revolving firearms.