Any info greatly appreciated,bought at yard sale,rivit construction,web carry strap,50 cal,never seen one before what is it for?

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No Idea. I just had one exactly like it, that I sold. I think it may have been used for transporting aircraft ammo. but thats just just a guess.

Thanks Jerry,I thought maybe aircraft ammo box too.Must be kind of scare as its the only one I have ever seen.