So just to be straight, if the damascus barrels are tested and are solid then it is okay to shoot the low pressure, low velocity shells. If they are not then you can go the tube option if the weight and feel of the gun are not to be adversely effected.
That sums it up quite nicely.
Although, to be fair, there are damascus barrels that are plenty strong to take any shell you an shove in it. I have a buddy that shoots a damascus Gibbs and he's shot from Argentina to Zimbabwe with anything he can find to stuff in the chamber.
Most of my guns fall into that category too, from a barrel thickness perspective, but I always figure, why not use nice light shells. I can shoot a flat of shells and worry a lot more about burning my fingers on the barrel than what my shoulder feels like.
