What's wrong with this?
I can't build a muzzleloader starting from scratch with some steel and wood, but these guys can. I doubt that many of the better known builders look much different when they're building a gun.
From what I've heard from the reenactors I ask about them, many Indian guns are functional and have locks that spark well, especially those from Loyalist Arms. Anyone who can build a functioning flintlock lock from raw materials has some real skill.
The biggest concern I have with them, after research and pissing people on several forums off asking about them, is that you don't know that the barrels are made to be barrels. They might be, but no one seems to be real good and determined to make it clear to me that they're using real barrels. Until I know I can sight down the barrel without worrying about my gun turning into a pipe-bomb, I'll pass.