About 3-4 years ago, I was given 7 lbs of Hercules Infallible powder with no idea of date of manufacture. Hercules Infallible was manufactured between 1898 and 1948. I have been using it for .38 Spl Cowboy Action loads for the last 3 years and I have enough loaded for 1 more season of shooting. Every time you come across propellant that has been manufactured 20+ years ago, you must consider the packaging and the storage conditions if you know them.