When we retired, the 4473's were sent to some federal depository.
The other records were taken by the NYC PD.
Some 25 years later I was contacted by a Police Department who had traced a revolvers from the manufacturer through to my old shop.
The 'detective' insisted that I had to tell him about the purchaser.
I advised him as tio how lost he was!.
NYC PD records department finally told him the name of the Police Officer who had purchased the weapon from our shop.
But, the trail ended here.
The officer had retired, moved out of NY State and had deceased.]
Of course , the search came back to me again several times.
At long last they believed that I no longer had the books/records