1. We know the pressures of the shells for which Pattern Welded barrels were designed.
2. We know that the "rough forged tubes" were proved in Belgium, and we know that the finished barrels were proved by the U.S. makers at about 1 1/2 X those pressures. And from Bell's, and others, destructive testing there appears to be a significant margin of safety before bursting.
3. We have a pretty good idea as to the original wall thicknesses of those barrels.
4. We know that (unabused) pattern welded barrels do NOT weaken / delaminate / internally rust over time.
5. We know that bad things can happen to barrels over 100 years so NO barrel can be presumed "safe" unless it has been evaluated by someone with the interest, tools and expertise to do so.
