In June 1955, Colt’s Mfg. Co.’s new masterpiece, the Python double-action revolver, was first shipped from the Hartford, Conn., factory, beginning a half-century of continuous production.

A first-year-of-production Python, serial number 170 went for $17,250. Another went with a high bid of $8,050, although about two dozen rather run-of-the-mill production models averaged somewhere ...