Step 2 is unlikely to happen. Someone who is not permitted to own a firearm by law cannot buy one from a licensed dealer thus the firearm will only be confiscated if the owner subsequently commits a crime. A legal owner with a legal firearm will not turn it in at a police buyback because 2 to 50 times as much money can be obtained by selling it.
Firearms confiscated or turned in at buybacks are typically either illegally owned, badly deteriorated, or have been illegally modified.
