The blown barrel does not explain the mangled hull. Rather, the explanation behind the blown barrel obviously lies WITH the mangled hull: possibly obstruction, possibly unintentional overload or other error in the reloading process. But at any rate, something caused the charge to blow out the sides of the hull as well as the end. (Great photos, BTW!)
As someone else suggested, whatever caused that gun to blow--given the obvious condition of the hull--might well have caused an 870 to blow. (Note the pictures of a blown-up M-1. Can't remember any of our weapons instructors in the Army warning us about that possibility, nor did I ever see it happen. But it quite obviously did in the case of the gun illustrated in the above post.) Thus, steel barrels also blow. As to asking for a guarantee from a modern manufacturer to produce a gun with Damascus barrels . . . seems I recall Greener was going to do just that. Others may remember more. The problem is not the inherent weakness of Damascus, but rather the expense of making Damascus barrels in comparison to fluid steel. But at any rate, the gun in the photos quite obviously did not blow just because the barrels were Damascus. That catastrophic failure had considerable assistance from some sort of problem that also impacted the shell itself. (Again, either an obstruction, like maybe a stuck base wad, or else an improper reload.) We don't know for certain whether the same conditions would've blown a modern steel barrel, but I feel pretty certain that even if it hadn't, the shell would've come out of the gun looking pretty much the way it does in the photos.
