Absolutly, if it hasn't been exposed to excessive humidty or contaminated it will be fine. I did read something a while back concerning old powders. The piece said that all powders have a specific level of moisture present in them. If stored for long periods of time in a very dry enviroment, they tend to get a bit stronger beacause of the moisture/weight loss due to the drying/aging process. Charges by volume have no negligable changes, charges weighed have more powder by weight because if the moisture loss.