Yeah, I wondered about that George. I've always read that the original bands were forgewelded into a tube. That would be a pretty difficult setup to forgeweld strips like that. I guess if they were 3/8" or thicker it wouldn't be too bad. At the right temp, they just have to make contact to weld.
I always wondered that if you forge-welded the inner tube from strips with one edge beveled slightly, heated the finished tube and twisted it around a form giving a helical twist, if you could essentially weld up a "rifled" barrel. Might be interesting to try on a smaller scale.