Ship them however you want. They do not fall under any FFL shipping rulings. I think they classify them as non-guns, more or less. That might be a stretch, but there is no issues with mailing one any way you want.
Wouldn't this only hold true if the Encore was barreled in anything other than true BP. One barreled for 6.8mm, .223, etc., would obviously not be a BP pistol. I assume this is to what you refer. He did ask about BP
Because the receiver on the TC (Encore & contender) is considered a firearm by itself (and because it has the ability to accept rimfire and centerfire barrels), it must go to a FFL, regardless of what barrel it has, or if it has a barrel at all.
Some other blackpowder rifles have this same requirement, because they make centerfire barrels for it.
I agree that a black powder revolver SHOULD be ok BUT with the conversion cylinders now on the market for cowboy action shooting, they accept cartridges. Why would this be different than an encore? It meets your line of thinking. I'm just sayin'
I have taken two deer with a Walker colt repo. What a hoot!