Might be a stupid question, but I honestly dont know.. I've always bought single lb's at a time, but this time I got my hands on an 8lb can of CFE223. I plan on using it almost exclusively for my .308, but 8lbs is enough for almost 1200 rounds of .308.. How long will the powder stay good after its opened, if its kept in my garage? Garage stays cool / cold all year long, and I live in a semi-dry environment. Thanks.