In upstate NY, if the firearm in question is a handgun, at the very minimum both parties to the sale need a valid NYS Pistol Permit and the seller needs to cross the serial number off his pistol permit, the buyer needs to add it to his. NY laws change every few years. In the 1970s you could do this on the back of the permit with a ballpoint pen, in the 1980s it was done on a separate document, nowadays I am unsure of the procedure, but some record MUST be kept of the transaction and both parties need a valid NYS pistol permit. Failure to make a record of the transaction or transfer to an individual without a permit is a felony and both parties would be prosecuted. So discussing CO private party transfers in a NY gun forum seems pretty stupid.