You cannot have (without a tax stamp) a lower that is mil-spec due to the milling that will allow it to accept a fully auto or tri burst FCG. It takes an extra hole in the lower. The 14.5" barrel was never mentioned by me because you can legally own one without a tax stamp as long as it is pinned or welded. Hence why I say it is not Mil-spec, it cannot accept the FCG without modification. They are made from the same materials. They are made with the same process accept the FCG(milling). This is by BATF regulations. Under their provisions it cannot accept the burst or fully auto group without modification. That was my only point. It isn't like the only difference is a DIAS, or a lightning link. But the materials are the same.
" The strongest reason for the people to retain the right to
keep and bear arms is, as a last resort, to protect
themselves against tyranny in Government...." - Thomas Jefferson