Believe it, its called COBIS for "Combined Ballistic Identification System" like I said I dont know which states actually use it but that is what the spent casing is for. The below Q and A's are from the New York State Police website.
Q - What are the responsibilities of a licensed dealer in firearms upon receipt of pistols and revolver into inventory?
A - A dealer in firearms that receives a new pistol or revolver from a manufacturer on or after March 1, 2001, shall upon receipt, ensure that the firearm is accompanied by a properly completed and sealed approved container enclosing a ballistic sample.
Q - What are a gun dealer's options if the manufacturer fails to ship a cartridge casing with a pistol or revolver?
A - A licensed dealer in firearms has two choices in such cases. Within 10 days of receipt of the firearm he or she can either:
Send the gun back to the manufacturer (or distributor or importer) and inform them of the obligation to provide a cartridge; or
Take the gun to a regional CoBIS Center operated by the State Police, where it will be test fired and the cartridges will be submitted directly to the CoBIS databank.
Q - When does a licensed dealer in firearms have to submit a cartridge supplied by a manufacturer, and to whom must it be sent?
A- Within 10 days after retail sale and delivery of the pistol or revolver, the licensed firearms dealer must send the cartridge casing along with the usual P-12 form to:
New York State Police CoBIS Center
Building 30, 1220 Washington Avenue
Albany, NY 12226-3000
Here is a link to the FAQ section of the New York State Police re: their COBIS program,
CoBIS FAQS (Combined Ballistic Identification System)