Owning a system designed for surface to air weapon carries life imprisonment any USA, without any intent for violence, just simple possession or conspiracy to possess[]. Doesn't even matter if you have an NFA stamp, there is no exception except if it's done with authorization and behalf of the government.

Merely having a device intended to guide the rocket is also the same penalty.

[] https://www.law.cornell.edu/uscode/text/18/2332g