Rigby barrels on American rifles.

Marlin-Ballard rifles offered a “Rigby-Finish” barrel, using the design that John Rigby introduced to American on his muzzle-loading rifle. John Rigby, the Dublin, Ireland maker not only imported Ballards but used them personally in competition, his targets were used in Ballard advertisements. The barrels with the Rigby flats are not Rigby barrels just Rigby-style barrels and have the normal rifling found in other model Ballards.
More on this subject can be found in John Dutcher’s excellent book on the Ballard.

Rigby-Style flats on American rifles were found on the Sharps 1877 long range and both Remington Hepburn and rolling blocks.

MP Sadly Deceased as of 2/17/2014