I'm pretty certain that the lug was originally attached with silver solder. The area does have a yellow/bronze color to it.

I thought that a full bead TIG weld might result in a stronger bond with less worry about warping or loosening the center ribs on the barrel. I am not sure whether the TIG weld would risk penetrating or hardening such thin barrels.

My main concern is the strongest bond with the least risk to the rest of the solder joints on the barrel.