Thanks for allowing me to add this info:
Only nine states have made Ballistic Knives illegal: California, Colorado, Florida, Idaho, Illinois, Indiana, Iowa, New Jersey, New York, North Carolina and Pennsylvania. In addition, they may be considered illegal in Washington State as well due to that state's odd switchblade ban statute with its vague definition of a "spring blade knife." Likewise, that phrase is used in Ohio's ban on manufacture and sale of "switchblade, springblade, and gravity knives" (SB 242 has been introduced for 2018 to remove this prohibition on manufacture and sale). There have been no judicial decisions supporting these possible interpretations, however.
While interstate commerce is generally illegal after the 1986 addition of ballistic knives to the Federal Switchblade Act, that doesn't preclude anyone from from producing or selling or possessing in any particular state, that is up to state law. As with the FSA, ballistic knives are also illegal on Native American reservations, territories like Puerto Rico, Guam, Northern Marianas, U. S. Virgin Islands and American Samoa and certain maritime situations such as Navy vessels or government-owned aircraft.
See an annotated copy of the FSA at:
https://kniferights.org/resources/federal-switchblade-act/
So, to sum it up, in 40 or 41 states there are no prohibitions on possession and carry of Ballistic Knives that don't apply to knives generally.