A freind of mine has many thousands of rounds of .22 in sealed quart canning jars. They have been in them for 60 years, and seem to work fine.
He used them in a monumental rat hunt in 1957.
http://gunwatch.blogspot.com/2016/05/wi-recond-rat-hunt-in-wisconsin-in-1957.html
He should have saved them for a monumental rat hunt in the former District of Columbia swamp in 2018. Or thereabouts.