So whats up with the F'N Hazmat fees ?
Since SAMMI is only concerned with ammo, they don't worry about components. That's what the hazmat is all about, powder and primers. Ammo is shipped all the time without haz-mat fees.
This did not answer the concern of some with storing ammo in sealed ammo cans, or powder/primers. Again, SAMMI is not concerned with it. Get mythbusters to do a program on it.
My suspicion is it would be similar to the open air results in the video. In order for shells in an ammo can to be a bomb, ALL the ammo would have to cook-off at precisely the same time to be a problem. That would be just plain impossible.