From The Federalist:

Ammunition laws are provided in several different flavors, all of which leave a bad taste in the mouth. Some, like those in D.C. and New York City, criminalize the actual possession of ammunition. Others, like legislation that just survived legal challenge in California, either tax ammunition or attempt to track it through microstamping–think tiny, engraved numbers. Although billed as measures to curb violent crime, the reality is that these laws are practically incapable of doing anything but raising costs and giving headaches to lawful gun owners.