Marlin Model 1898 Slide Action Shotgun was advertised with "Special Rolled Steel" (Decarbonized Steel) having an ultimate tensile strength of 66,000 psi.
July 11, 1903
Sporting Life stated “barrels of Special Smokeless Steel” presumably the higher grades
https://digital.la84.org/digital/collection/p17103coll17/id/39596/rec/48 September 22, 1906
Sporting Life Model 21 introduced
https://digital.la84.org/digital/collection/p17103coll17/id/34688/rec/78 September 28, 1907 ad
https://digital.la84.org/digital/collection/p17103coll17/id/33486/rec/83March 7, 1908 Model 24 introduced
https://digital.la84.org/digital/collection/p17103coll17/id/33711/rec/84 Marlin Model 26 Trap in 1910 with "Special Smokeless Steel"; tensile strength over 100,000 psi
Marlin Model 28 Trap in the August 2, 1913
Sporting Life "New Marlin Hammerless Trap Gun" still with "Special Rolled Steel"
https://digital.la84.org/digital/collection/p17103coll17/id/57520 
Model A "Special Rolled Steel" 1913
B&C "Special Smokeless Steel"
Marlin “Special Smokeless Steel” was introduced for the Model 1893 rifle in 1897 and Model 19 Grade C introduced in 1906, and Model 21 Grade C in 1907 with an advertised tensile strength of 100,000 psi. I have no data as to the composition.
Interestingly, the Stevens No. 350 double introduced in 1901 had “Special Steel” and in 1904 “Special Smokeless Steel”.
The No. 235 & No. 335 doubles were introduced about 1908 with “Compressed Forged High Pressure Steel”.
Western Field, November 1908
https://books.google.com/books?id=UB0LAAAAIAAJ&pg=PA197&lpg 
