A few years ago I built a copy of a Hudsons Bay Trade Gun. These are very historical for this part of Canada as many were imported into Canada and traded to the first nations people. I used a piece of DOM tubing to make the barrel. It took a bit of reaming but it turned out nicely as a 62 caliber smooth bore. I used a piece of hard maple with a few worm holes to make it more authentic. I enjoy shooting this but the stock could use a bit more drop for my big head.
Antique Rifle Restorations by the Gun Doctor 