I had a couple cans of atleast 40 year old bullseye their the square tin cans with a flange style pop top. The cans were new and unopened pull tabs still intact. when I opened them up the powder looked and smelled perfect I used most of it up in 38 special loads without any issues. that said from my experience if the powder was stored properly it should still be fine to use even after 40 years of storage.