There are a few gun makers around who have the ability to build a muzzleloader totally from scratch, but not too many. gunsmiths at Colonial Williamsburg do so. Also, the House Brothers, Hershel and Frank, from around Woodbury, Kentucky, are fully capable of this. I have flintlocks by each of these brothers that were formally Ford A-Model springs, 1941 International truck bumpers and wrought iron rims off farm impliments. These are the sources of metals most desirable for barrels, locks, etc. And then there's Jud Brennan up in Alaska. I have seen pieces made by Jud that were totally hand made and could not be identified as contemporary. It's possible, but not more than a small handfull of contemporary builders have the abilities to do so.