After watching a few episodes of Hoarders and Preppers I know where all the ammo has gone. There is no shortage of people who think the world is coming to an end in short order and believe that having 50,000 rounds of ammo will preserve place for them in New Eden.
Skans, this also is a high possibility.
With the proliferation of preppers/hoarders/apocalypse, other normal individuals have taken to the practice of buying excessive amounts of ammo and supplies to stash for their own, even if they are not preppers.
Some forum members have boasted over 20k of ammo; at first I thought 5k rounds was excessive before. Now 20k and up is the norm esp if you add 22lr to that amount. These hoarders/preppers who bought countless rounds of ammo before it dried up in January is definitely a cause for the shortage we currently have.