Someone is trying to tell me that putting an ATI top folding stock (with a pistol grip) on my Mossberg 500 is illegal. From my research, I think it is legal in Oregon. But, I couldn't quite confirm it. Sounds to me that if the barrel 18 inches and the gun with stock extended is at least 26 inches, it is legal. And adding this stock would not change the gun from a shotgun to any sort of other firearm with the ATF. Can someone confirm or point me to some document online that I could rely on?