I have a Rock Island Armory XM15-A1. Sendra was the manufacturer/supplier of the lower. If my memory serves me correctly Rock Island Armory was a branch (or some relation) of the current Springfield Armory (in IL). From what I remember they got into trouble with the ATF, Something about manufacturing illegal machineguns (probably paperwork issue). Anyway, they went out of business before any of the "bans". If your lower receiver has "Rock Island Armory" on it it is preban. Rock Island Armory only sold complete rifles.