William Siemens established the Sample Steelworks to develop the Siemens-Martin Open Hearth process in 1865, and his steel was in general industrial use 1870 - 1875.
Siemens is likely the steel used for the Wm. Powell "Punched Steel" barrels.
c. 1868 advertisement
"Metallurgy of Steel", 1905
http://books.google.com/books?id=RaF9AAAAIAAJ&pg=PA512&lpg As early as 1866, Messrs Deakin & Johnson, of Bilston, were making weldless rifle barrels from a steel block about 1 inches diameter and 8 inches long, by punching a hole from each end under a steam hammer, and then rolling the blank presumably in the same way as weldless tubes are now rolled in the process of "rolling off".
"Cold rolling" decarbonized and carbon steels increases tensile strength
