Gunmakers, then and now, made what would sell within a target profit margin. By 1870, Decarbonized Steel was the "new and improved" barrel material for shotguns. But Pattern Welded tubes were being produced cheaply and in great numbers in Belgium, and became the barrel material of choice for higher grade (more expensive) guns.
Sir Joseph Whitworth's adaptation of Bessemer's principle of hydraulic pressure casting was patented in 1874. The first Purdey Pair Nos. 10614 & 10615 were delivered January 1, 1880 with the "New Whitworth Fluid Pressed Steel", and Lefever Arms Co. was the first U.S. maker to supply Whitworth steel for their Optimus in 1887. More "new and improved" steels proliferated rapidly thereafter.
From 1897 Consular Report: Commerce, Manufactures, Etc, Volume 54
United States Bureau of Foreign Commerce
http://books.google.com/books?id=SF1...J&pg=PA526&lpg
Prices for a pair of rough forged tubes show decarbonized was much cheaper than pattern welded:
Steel................... $0.58 (3 francs)
Twist................... $1.16 (6 francs)
Oxford 3 Stripe.... $2.90 (15 francs)
Boston 2 Stripe.... $1.93 (10 francs)
4 Stripe Crolle’...... $4.825 (25 francs)
Unfortunately, I haven't found the cost for Belgian
fluid steel made by
Laurent Lochet-Habran or
Cockerill Manufacture Liegoise
When Crescent introduced the Model 6 sidelock hammerless double in 1904 with "Armory Steel", decarbonized had obviously become the choice for utility grade guns.