This was in a thread a while back. Two men were prosecuted in Kansas for building a suppressor and a SBR, relying on a Kansas statute stating that Federal law did not apply to firearms made, kept and sold only within the state. The Federal court found them guilty and upheld the Federal law over the Kansas law. The Court did find that they had a "good faith belief" that the Kansas statute protected them, and on that basis gave them probation instead of prison time. Both now have felony convictions though, so they cannot possess firearms.
I don't know what level of legal advice they obtained before they went down this road.
I don't know what level of legal advice they obtained before they went down this road.