This FAL and the others that I have built are head spaced and tested to safely shoot both 7.62x51 NATO and 308 Winchester. It is generally accepted that using 308 Win for rifles chambered for 7.62x51 NATO is "Not A Safe Practice"! It is generally accepted that using 7.62x51 NATO in a rifle chambered for 308 is most likely safe. There are always exceptions to anything and if you are unsure as to your rifles chambering, head spacing and general condition consult the manufacture or a competent gunsmith!