Dave: Parker Brothers "Gun Iron" barrels were made from surplus musket barrels used on "Charles Parker Makers" guns. This is an 1866 Price List
Decarbonized steel by Remington was new fangled stuff at the time
From
Fire-Arms Manufacture 1880 U.S. Department of Interior, Census Office
"The earliest use of decarbonized steel or gun-barrels is generally credited to the Remingtons, who made steel barrels for North & Savage, of Middletown, Connecticut, and for the Ames Manufacturing company, of Chicopee, Massachusetts, as early as 1846. It is also stated that some time about 1848 Thomas Warner, a the Whitneyville works, incurred so much loss in the skelp-welding of iron barrels that he voluntarily substituted steel drilled barrels in his contract, making them of decarbonized steel, which was believed by him to be a a novel expedient. The use of soft cast-steel was begun at Harper's Ferry about 1849. After 1873, all small-arms barrels turned out at the national armory at Springfield were made of decarbonized steel(a barrel of which will endure twice as heavy a charge as a wrought-iron barrel), Bessemer steel being used until 1878, and afterward Siemens-Martin steel."