I used teak because it contrasted the brass barrel nicely, finishes well, and is a nautical material...not to mention I had it arround. If working with a steel barrel I'd propably blue it or paint it black and use a lighter wood like ash or hickory, or paint for contrast. A voluteer at the fort in St. Augustine told me the wood used for carriages depended on what was locally available and the finish was originally oil. Teh oil finish would darken over time and eventually resemble paint. Their's were painted.