QUOTE (AnonymousD @ October 20th 2009 1:15 PM)

I built a pistol on a non-pistol marked lower. You can change it to a rifle at any time you want, but you CANNOT go back from a rifle to a pistol.
As long as it was originally registered as a pistol and you remove the stock BEFORE you put the pistol upper back on, you can go back to pistol. Also if it was originally registered as a pistol and you do convert it to rifle and decide to sell, it has to be sold as a pistol regardless of what configuration it is in.
You can have any length barrel you want on a pistol lower, including rifle length. You just can't have a barrel shorter than 16 inches on it with a stock attached or it is a SBR. Remove the stock and then put the pistol lower back on and you are GTG.
Got to love the convoluted BATFE laws.