I would tell you to start at Numrich Gun Parts, and when they tell you they don’t have barrels for it, sell whatever is left of the gun to them. At that point, take whatever they give you, and if the notion of a Spanish .410 intrigues you, begin the search for a functional gun.

You’ll have a couple bucks head start.

.410 double gun barrels would be difficult to source for that gun.

Best,
Ted