JB is correct, (as usual). Springfield did not toss any receivers away. Rock Island did just that. Indeed, the usual "around 800,000" warning implies a very few receivers slipped by the 800,000 serial number. However, a serial number around 779,xxx may well be OK. Trouble is, none of us know of any way to tell for certain. New brass and moderate loads should do the job. Let me add this as well: I do not shoot any of my low numbers, as I have many nice high number '03's. Good luck.