Taking the paragraph directly from Speer manual #11:
Primers should be stored in a cool, dry place that is free of great temperature fluctuation. Under these conditions, shelf life of modern primers is virtually indefinite; they will certainly develop their full performance potential for many years. Normal room temperature is quite satisfactory for primer storage. More than room temperatures will cause no problems assuming again that primers are not exposed to excess atmospheric moisture. But exposure to high temperatures (over 100 deg F) for an extended period will cause deterioration of some vital primer constituents.
I've kept mine in their original containers and stored in a large plastic tote in a closet. I have and am using primers and powder I bought in mid to late 80's without issue.
Primers should be stored in a cool, dry place that is free of great temperature fluctuation. Under these conditions, shelf life of modern primers is virtually indefinite; they will certainly develop their full performance potential for many years. Normal room temperature is quite satisfactory for primer storage. More than room temperatures will cause no problems assuming again that primers are not exposed to excess atmospheric moisture. But exposure to high temperatures (over 100 deg F) for an extended period will cause deterioration of some vital primer constituents.
I've kept mine in their original containers and stored in a large plastic tote in a closet. I have and am using primers and powder I bought in mid to late 80's without issue.