Bessemer/Decarbonized Steel is NOT the same as Charles Parker Makers "Gun Iron" barrels which were made from surplus Cast Steel musket barrels.
c. 1866, Parker offered 'Plain Finish-Iron' Barrel for $50, 'Superior Finish-Iron' Barrel for $75, and 'Laminated Steel' barrel for $100. In 1869 Decarbonized Steel was listed for the $75 grade, and in 1874 “Plain Steel”.
1866 catalog courtesy of Richard Hoover