From 1984 to 1991, Federal Ordnance of South El Monte, California sold a semi-auto version of the M14 rifle. Initially named the "M14" or "M14A", the rifle utilized an aftermarket semi-auto receiver fitted with surplus USGI M14 parts. All receivers were machined from castings of AISI 8620 alloy steel. Except for the first fifty receivers, the castings were supplied by Electro Crisol Metal, S.A. of Santander, Spain, then imported to the US for heat treatment, finish machining, and exterior phosphate treatment. M14 and M14A receivers were heat-treated using the carburizing process by a firm in Santa Ana, California, followed by finish machining on a CNC machine at Federal Ordnance in South El Monte.