ORIGINAL: devil dog
Definition of a firearm; any weapon "includeing a starter gun" which will or is designed to or may readily be converted to except a projectile by the action of a explosive. So your answer is no, a felon cant own or have in possesiona muzzle loader by definition, he cant even own or posses abullit proof vest, if he wants to hunt, the only thing he can use is a bow.
Several, if not the majority of states allow the use of mz's by anyone.
Someone intent on commting a new felony with a firearm will probably not choose a mz as their preffered weapon.