After searching some about the acc. barrel program, I have a question. Please forgive me if it has been talked about before, but I couldn't find it in the FAQ section. After an accessory barrel is fitted at the factory, does it only fit the one receiver or can it be switched around on other rifle receivers? I know you can't use a rifle barrel on a shotgun receiver but was just wondering if I would be limited to using an extra barrel on only one receiver. Thanks!