It's ole Belgian shoty with demiblock barrels. If I recall correctly Herr Piper or Pieper was first one to use this barrel jointing method producing assembly line SxS shotguns late in 19th century. Assuming good mechanical order, enough barrel thickness, no pitting you will need low pressure custom loads to use that gun. I luv the "poison ivy" wine decoration it is quite unique.
I believe the barrel construction is what we call monoblock today. This method was first introduced & patented by Henri Pieper though to my knowledge he never used that term. His first version was constructed different from his one, though he did later use a similar process, though not sure if he had a patent in the modified version or not.
To my understanding demi-block is another term for chopper Lump, a totally different joining process.
