Black Powder Firearms, and their replicas, are NOT considered firearms if it is a pre-1900 design, AND if it uses percussion, flint, match, etc., ignition. It is only regarded as a firearm if it is used to commit a crime. It's interesting when you take into account the power of the Colt Walker, it's still one of the most powerful handguns in the world. While we're on this note, I think low power, low calibre (as if there are other kinds on the market today) rimfire firearms should have similar rules as the BP firearms. :uzi:
BTW: In regards to felons and minors, that's sort of a grey area, and legal action will usually depend on the mood of the police officer or the DA. Unless you're in Kalifornia, where any type of firearm, or device resembling one, is outlawed.