TOTW may be attractive for your Hawken but if you are serious about building one of these, do it right and look up don Stith (
http://www.donstith.com/muzzle_loading_rifles.html) or The Hawken Shop (build Hawken rifles from original patterns and tooling of the Hawken Bros.). May be a bit more pricy but you get what you pay for. Most original Hawken rifles actually had a tapered barrel vs a straight barrel.