I have to tell you that IMHO no Damascus barrel shotgun should ever be fired, not even with black powder loads.
No offense but that is as you stated YOUR opinion. It's not mine. As long as the barrels are in good shape there's nothing wrong with shooting moderate bp loads out of them. I've been shooting them for many years. I have an Ancion SXS muzzleloader made in Belgium around 1840. It's a great shooter and those older guns handle much better than the new ones.