A new rule quietly floated by the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) would outlaw millions of guns and turn gun owners into criminals.

The ATF published a notice last Thursday that it intended to outlaw the AR-15 pistol and similar firearms and that existing weapons will have to be destroyed, turned over to authorities, and owners to register.

The AR-15 pistol uses an arm brace system to stabilize the firearm as it is being fired. The pistol needs this brace because the AR-15 pistol is the essentially the same firearm as the AR-15 rifle but with the shoulder stock removed. There are as many as 4 million of these type of weapons in the U.S.