The marijuana issue already had its day at SCOTUS in Gonzales v. Raich, and lost. It was a bad decision, saying that the federal government can regulate something based on the most tenuous connection to interstate commerce, but it it the law of the land. Raich was the basis for the 9th Circuit reversing its original decision in US v. Stewart; they had previously overturned a conviction for possession of an unregistered machinegun on interstate commerce grounds.
These Firearm Freedom Acts have good intentions, but at this point I'm afraid it is going to take either a constitutional amendment or a major change in the composition of SCOTUS to rein in the federal government's trampling of states' rights.