Ed Rayl can make one too, I'm sure. I have a barrel I picked up from him about a year and a half ago with a 1.03" breech, about 1/10" taper and only about 1/32" flare at the muzzle, 43 3/4" long. He said it was an exact copy of a WV rifle from around 1820 from his own collection. Mine is .45 caliber, but you could ask him about getting one in a larger caliber.
I'd suggest a GM barrel and a coarse file, but they only go up to 15/16 thick in .50 x 42, a little small for a later flint trade rifle (which is what I'm guessing you are looking at....)