The Montana Firearms Freedom Act [1] is an attempt to limit federal jurisdiction over firearms in the state of Montana.
Provisions
The law declares that firearms manufactured in the state of Montana after October 1, 2009, and which remain in the state, are exempt from United States federal firearms regulations, provided that these items are clearly stamped "Made in Montana" on a central metallic part.
It applies to all firearms other than fully automatic weapons, firearms that cannot be carried and used by one person, and firearms with a bore diameter greater than 1½ inch which use smokeless powder. It also applies to ammunition (except exploding projectiles), and accessories such as silencers.[2]
The law has no requirements for registration, background checks or dealer licensing.
http://en.wikipedia.org/wiki/Montana_Firearms_Freedom_Act