Indeed Lloyd, but two points. The pressure increase was unlikely to have been linear. And these were specially bored 30" barrels without chambers and with wall thickness of .150" at 3", .092" at 6", .048" at 12" and MWT of .035 at 21".
Additional commentary found in Frederick Toms’
Sporting Guns and Gunpowder, “Experiments On the Strength of Gunbarrels” regarding an additional study comparing brazed and unbrazed Steel and Damascus barrels:
http://books.google.com/books?id=inQCAAAAYAAJ&pg=PA14&lpgThese experiments serve to show what a very large margin of strength there is in a good gun barrel, when ordinary charges are used. The (Damascus) barrels which gave way earliest...had withstood the strains of…about four times as great as the regulation proof; while the steel barrels (Siemens-Martin and English “Superior Barrel Steel”) were tested...with charges averaging nearly five times as much as the ordinary proof-charge.
Although the steel barrels showed the greater amount of endurance,
the strength of the Damascus was so much in excess of all ordinary requirements that no fear need be felt of their giving way when the work is properly done.
