The patent damascus chopperlump barrels were indeed proper CL barrels with the lump forged as part of the tube. Not to be confused with a tube set that has had a lump added by any method. I have seen a couple of examples of the patent but a while back and can't remember the nature of the patent mark. At least one was at Holt's and you may be able to find it by searching their archive of old auction catalogues.
Steve, yes, the problem was that the damascus lump was too soft to give long term service and I remember reading way back that these barrels nearly always have a dovetail repair to the hook using 'normal' steel. However, this is the norm with well used guns with vintage repairs. I think it is fair to say that some truly awful steel was used for all sorts of applications in Victorian gunmaking - metallurgy being a 'black art' back then. The best materials were sourced by the best makers but probably the 'best' supplier had only a vague understanding of WHY there products worked. They knew how to get there but it was a form of alchemy!
