In 1855, Colt introduced a new revolver unlike the others in their lineup - it was a side-hammer design with the cylinder stops built into the axis pin instead of the cylinder. They then proceeded to scale the design up into revolving rifles and shoguns in several calibers. The revolving shotgun model was the least-produced, with only about 1300 made between 1860 and 1863. This example is in 10 gauge, and has five chambers in the cylinder.