IF it is stored correctly, i would say a shelf life is 50-70 years. if it is stored under perfect conditions, ( primers and bullets sealed, and in a ammo can with a good seal, and in a fairly stable, normal temperature), you could get good results up to 100 years. but, if it has been in the back of your pick up truck in a tool box just bouncing around, in the hot sun, cold winters etc., maybe as little as 5-10 years. now if it was just thrown out in the weather, not protected at all, i would only give it a year or so, if that. just my opinion, as i have no facts on any of this. but i have shot my share of really old ammo, and it always goes bang. maybe not with the authority it once had, but still it does fire.