Hi Buckshot, the barrels will be joined using lead, the heat required to join the barrels with silversolder will warp shotgun barrels.
Shotguns can be blued, but not in the same manner as we normally use to blue rifles. If cost is an issue, have it ceracoated - it will look and function great.
If you would really like to have the gun blued, go ahead and do some research, there are some really great gun smiths in NZ that would be able to help. Experience in regards to shotgun blueing and maintenance is essentiale.
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