I was reading through the NY Times liveblog of the protests in Egypt, and in the 9:19am update, there was a series of videos and pictures. One of those pictures was of one of the oft-mentioned US-made tear gas canisters.
What jumped out at me, more than the fact that it was made in the US, is that the canister expired 5 years ago. Just at the top of the shell, two lines of text are visible:
3. SHELF LIFE 5 YEARS AFTER DATE OF MANUFACTURE
4. DO NOT USE AFTER EXPIRATION DATE
And then of course, there is the big sticker which reads “MFG 2001”. And since “MFG” is a fairly standard abbreviation for “manufacturing”, it would seem as though the canister expired some time in 2006.