I started reloading in 73 and all my Bullseye, 2400 and Unique came in the tubular cardboard canisters......like what we buy today. I have accumulated various types of powders dating back into the 50's and loaded with them without any misadventures. If it is stored properly powder will last a long time.
2400 has always been my "go to" powder for magnum loads, particularly in the longer barrels.