Well, tgreening, I wish I could have been more help. Unfortunately, even though I am a lawyer, I am still in the "shallow end of the NFA pool," in terms of my knowledge of relevant law, so I'm reluctant to do anything other than point you to a statute or a ruling.
A gunfight is not the time to learn new skills.
If you ever have a real need for more than a couple of magazines, your problem is not a shortage of magazines. It's a shortage of people on your side of the argument. -- Art Eatman