It has something to do with interstate and intrastate commerce. Montana is in essence claiming that as a State they have the right to control what goes on in their state. And they believe that anything produced and sold within Montana should be out of the Federal Governments jurisdiction.
I heard on Beck last week that many of the States believe the Federal Government have overstepped their bounds through the mis-use of a commerce law. This abuse took hold under FDR in a case that involved a farmer.
http://www.glennbeck.com/content/art...cle/198/25060/
So the rumor is Montana is going to produce a single shot 22lr rifle in Montana and test the waters.