Goex black powder has an unlimited shelf life if kept in a cool dry place in its original container. As for Pyrodex, the loose powder should hold up just as well if properly stored, but i have heard that it will lose its potency over a few years. I cannot attest to that, as I only use real black powder. You might want to check out any local hunting clubs in your area about getting real black powder. At my club, we pool together our order to Maine Powder House. If we order 25# or more we get the shipping and haz-mat fees free.