Ask your local chief LEO if he has a inventory of all firearms taken off the streets in a year or so. If he does, ask him if he would be willing to let you and lawyer into the arms room to do a check.....
No one ever see these inventories. Ever.
I have LE acquaintances who have offered to let me pick through such inventories of weapons ( ones that were no longer needed for process). Do you wonder where the money would have went? I politely declined and lost contact with those types. Love of money is the root of all evil.
At least here in MO, now LEAs that want to rid themselves of firearms have to sell them to a FFL dealer, they cannot trade them, they cannot destroy them (unless they are defaced etc). The jurisdictions chief executive must certify the lists and the funds must go into the LEA general fund.
No chief that wants to keep his job and his personal freedom would allow anyone without a LE clearance access to the evidence vault. Furthermore, ours is inventoried and audited twice a year, once internally and once externally. The Chief of Police cannot even step into our evidence vault until he has signed in and has to be escorted.
And my agency destroys EVERY gun when either the case is closed or no owner claims them.
There is no official use or sell back to public. We do sell our old issued firearms to FFLs, but not evidentiary, found or voluntarily given to the department.
Here is where ours go...
http://fox2now.com/2017/05/18/gunbusters-destroys-confiscated-firearms-with-6000-pound-pulvervizer/
All video taped at the time to maintain chain of custody from our evidence custodian to the folks crushing them.
You live in Missouri which has large Democrat controlled cities such as St. Louis and Kansas City. Democrat cities tend to be corrupt so what you described to me seems like a perfect scenario for a dishonest business of selling second hand guns on the side.