The gun used by Vance (Robert F. Simon) was stated to be a .36 caliber revolver. A close up shot when Vance is holding his gun on Longley reveals that it is actually a Smith & Wesson, double action, top break revolver. Most likely a S&W 4th model top break revolver in .32 caliber produced between 1883 and 1909. These revolvers were never made in .36 caliber which was a black powder cartridge.