Just curious about selling a AR pistol. If I wanted to sell my AR pistol that I built from a stripped lower how do I proove that is the original configuration? The hypothetical sale would involve a FFL. I plan to ask my FFL this question but I thought I would toss it out here and see if you guys/gals have experience with this. I am aware that a purchased rifle cannot be converted to a pistol and a pistol can be converted as long as the pistol upper and shoulder stock are not on the firearm at the same time making a illegal SBR.