The obvious reason for this common thread is that if a gun entered from another state, the argument that it falls within federal jurisdiction under the Interstate Commerce Clause can be invoked. However, such an argument would be incorrect.
Congress has the power to regulate interstate commerce. Just because a gun crosses state lines does not mean it did so as a part of commerce. Many people move from state to state and take their belongings, including guns, with them. This is not commerce.
Secondly, there is a temporal issue raised by assuming any gun that has come from another state is within the ambit of federal regulatory jurisdiction. As stated, the federal government is empowered to regulate interstate commerce. But what if a gun entered a state as part of interstate trade in say, 1980, and here it is 2010? The gun is no longer the subject of any act of interstate commerce and has not been for 30 years. It is specious, at best, for anyone to believe that any product that ever was the subject of interstate commerce forever remains the subject of federal regulatory control. Read more