As posted several times, the 1903 rifle will fit into any a3 stock because all a3 stocks are also inletted for the 1903 rear sight collar along with the a3 forend ring. The 1903 Trigger guard will fit into any a3 stock too, although it will be extending out of the wood more then it would the 1903 stock. If you attend gun shows you can easily see if a 1903 rifle is installed into a a3 stock just by looking at the ring cut on either side of the stock Inletting where the sight collar & receiver meet.