Such weapons are also not considered firearms under federal law. You can buy them without filling out a form 4473 or going through NICS.(3) "Firearm" means any device designed, made, or adapted to expel a projectile through a barrel by using the energy generated by an explosion or burning substance or any device readily convertible to that use.
Firearm does not include a firearm that may have, as an integral part, a folding knife blade or other characteristics of weapons made illegal by this chapter and that is:
(A) an antique or curio firearm manufactured before 1899; or
(B) a replica of an antique or curio firearm manufactured before 1899, but only if the replica does not use rim fire or center fire ammunition.
You could legally carry one openly in places where CHLs are not allowed to carry, such as a bar.
However, I would not bet on the police being familiar with this nuance of law.
- Jim