Bramble,

The export license is needed for a permanent export from the US. A temporary export for personal use does not require an export licnes .

TSA has just issued a clarification on this subject.

Traveling safely with Ammunition

Additional information is found here:

Traveling with Special Items-Firearms & Ammunition

Of course this is U.S. requirements.

Airlines can issue even stronger restrictions and I think the lock box rule is an airline---SAA requirement. I know when I flew back from SA with ammo, they added tape to keep my MTM boxes closed.