Some are probably destroyed, and some are sold.

Many possible outcomes for an impounded weapon.

the NRA got into the act lobbying for some turned in weapons to be sold for profit.

the current discussion re guns and mass shootings involves legal firearms. Shifting the focus to what happens to illegal firearms is a red herring.

Particularly guns illegally obtain and used in crime. I see no valid reason why any of them should make it back out to the streets. This morning on Up with Chris Hayes, Goldie Taylor was telling about the life of the gun that had been used to kill her father. It was later used to commit another crime and she said she believes it is still out there today. Why not remove weapons that have already been used for crime from circulation and couple that reducing the number of people who can own them?

the problem is some smaller departments rely on the revenue made from selling crime and PD weapons when they are finished with them.

More than one PD has been caught using them as throw-downs