[i]Typically, the barrels are joined at the breach end by brazing, for both chopper lump and dovetailed lump. Then, the barrel tube area is heavily tinned. The ribs are fitted and "wired and wedged" into place while the whole assembly is heated sufficiently to flow the tin and join all parts together. With this process, regulation can be done by remelting the tin and shifting the barrels slightly. Brazed barrels require the whole barrel/rib/lump assembly be held in a jig and joined in one fell swoop. It is either right or not and remelt adjustment is not an option.
Henri Pieper developed an oven in the 1890's to braze barrels. One more step to speed up the production line. Loose barrels were proofed then brazed. After this they were then reproofed.
Pete
