But I thought illegal guns went in
Illegal guns come from a variety of sources. In some cases, residents of states where it’s easy to buy several guns at a time — and no records of the purchase are kept — act as “straw purchasers” who buy guns for people from more gun-restrictive states such as New York.
But authorities say about 75 percent of the illegal guns seized by Rochester police each year are traced back to New York residents who either lost them or reported them stolen.
Via Keep And Bear Arms.