Montana Firearms Freedom Act

The Montana Firearms Freedom Act is a state statute (since held invalid by Federal courts) that sought to exempt firearms manufactured in Montana from federal regulation under the interstate commerce and supremacy clauses of the United States Constitution. == 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.

Source: Wikipedia — Montana Firearms Freedom Act (CC BY-SA 4.0)