Jim, didn't Remington settle a class action lawsuit about barrel failures on either the 870 or 1100 (can't remember which)? Seems those would fit your description of either failure in the material used or the manufacturing process. Unless you're referring only to doubles? But if the fluid steel barrel on a pump or auto can fail, why not on a double? And I believe there have also been reported failures of either Krieghoff or Perazzi barrels--OU and not sxs, but again, modern fluid steel.
A the owner of a firm* that was involved in several firearms lawsuits I can only remember that Winchester was sued over the trigger design with their 1300 and 1400 shotguns. Due to this design the trigger could be pulled while the shotgun was being carried in one hand horizontially thru upward pressure on the trigger alone. We were also involved in the Glock accidental discharge lawsuits which may be still ongoing. The only other major lawsuit I'm aware of involves the trigger/safety design with the Remington 700 rifle series. If there has been lawsuits involving the above models I'm not aware of them. If anyone has information regarding additional shotgun barrel failure lawsuits please post it.
Again; ANY barrel on any firearm can and will fail IMO if subjected to enough pressure as shown above and this also appears to be a case of obstruction.
Getting back to the point of this thread which addressed the repair of pinholes. To me; A pinhole is a sympton of perhaps a far greater problem. Due to the manufacturing process involved in crafting damascus barrel voids were unavoidable and 100+ years of continued stress and perhaps rusting hasn't improve their durability. I have participated in and personally seen thousands of rounds of trap and skeet shot over the years and have yet to see a barrel failure with a modern shotgun occur while I was present. Shooting original damascus shotguns is a relatively modern phenominnum and I don't remember seeing any in use when I was actively participating.
*I am NOT an attorney and my firm was involved in the videotaping of depositions.
Jim
