Short version Lloyd
These numbers are all for gun barrel, non-heat treated steel
Twist and Crolle Damascus tensile strength is about 55,000 psi
Winchester Standard Ordnance and other "cold rolled" Bessemer/Decarbonized steels and AISI 1020 are similar in strength at about 60,000 psi
c. 1900 Belgian sourced “Fluid Steel” used by all the U.S. makers (Cockerill, Siemens-Martin & Krupp Open Hearth) and AISI 1030 are similar in strength at 75,000 - 85,000 psi
Krupp Fluss Stahl (Homogeneous Fluid Steel) was introduced about 1890 might be a little stronger
AISI 1040 (and modified), Vickers, Cockerill Acier Universel or Acier Special & Bohler “Blitz” are similar in strength at about 100,000 psi
Winchester Nickel Steel, Marlin “Special Smokeless Steel”, Remington Ordnance Steel, Krupp “Nirosta” (1912 patent NIchtROstender STAhl 21% Chromium / 7% Nickel Stainless Steel introduced in 1913), 4140 Chrome Moly (not used until after 1930s) and 4340 (Chromium, Nickel and Molybdenum) are all similar in strength at > 115,000 psi


It is important to remember tensile strength is only a part of the equation for estimating bursting pressure. If the barrel is made of Twist with a 50,000 psi tensile strength, that does NOT mean that it will withstand a 10,000 psi load by a factor of 5.

Barlow's formula P=2 S t / D
P=Bursting pressure in psi.
S=Tensile strength of material in tube wall.
t=Wall thickness in inches.
D=Outside diameter in inches.

Barlow’s refers to a pipe capped at both ends with a static pressure (a pressure cylinder). Shotgun barrels are not designed to be pressure vessels as one end is open and the pressure rises and falls quickly.


And this regarding the Proof House Trial
The five barrels tied in Phase 2 failed at 12.5 times the Definitive Proof load or 11.34 Drams with 2.82 oz. shot. It should be noted that the 12th barrel (because of ties) Foreign Pointille’ Twist failed at 5.77 times DP and the 13th (last) Foreign Four Rod Crolle’ failed at 5.74 times Definitive Proof.
The test barrels however had uniform dimensions, without chambers cut, and much thicker wall thicknesses that used on shotgun barrels.

A reassuring comment in Sporting Guns and Gunpowders regarding an additional study published in The Field June 6, 1891 by Horatio F. Phillips, a “staff experimenter” with The Field
"These 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."

To quote John Brindle’s summary of the Trial:
“Thus steel had proved stronger than Damascus in this test, but the strength of both was such that this did not matter one bit, such was the margin of safety in a barrel of either material of suitable dimensions and without flaws. And it was the purpose of regular proof tests to find those flaws if they existed.”