Five days after Vice President Joe Biden encouraged a ban on assault weapons, a Charlotte man pleaded guilty to buying and illegally selling them at local gun shows.

Gun show employees tipped off authorities to Michael Beas, 33, after he purchased large amounts of AK-47s, according to the Charlotte Observer.

But the investigation is being held back because authorities don't have a way to track multiple assault weapon purchases. According to the story:

Even today, authorities don't know how many guns Beas bought and sold, or who he sold them to.

Beas apparently traveled to shows in Charlotte, Hickory, Atlanta, Columbia, Greenville and Myrtle Beach. Authorities suspect he might have even smuggled some to Bolivia, his ex-wife's native country, though Beas denied such activity. He faces a maximum five-year sentence and $250,000 fine.

Read the Observer's story here.