http://www.foxnews.com/story/2004/05/19/tests-confirm-sarin-in-iraqi-artillery-shell/
Polish troops found two 122mm shells that tested positive for sarain and locals took them to a cache of 16 similar chem shells which may never have been filled. Iraq had to be careful as I recall on filling too many shells ahead of time as their chemicals were often impure and very corrosive or did not store well.