One 155 mm shell from his MYTHICAL arsenal has already been found.
I doubt if it is the last one.
One point that you seem to miss is how uneducated the Al Qaeda guys are. Mixing up a batch of such chemicals is much harder than draining a few shells.
Al Qaeda is all over Iraq right now. I am sure that they have access to such shells if any more are left.
And you can be sure that there are some left.
