The letter of the law is clear. Private sales between residents of the same state ok.
Common practice is often like the military don't ask don't tell.
No longer true or legal in NY. All sales must go through a NICS check, except imediate family, since the SAFE Act took effect here.
"1. General Business Law Article 39-DDD
GBL Article 39- DDD requires that all private sales of firearms, rifles or shotguns be conducted through a licensed importer, manufacturer or dealer. Before any private sales may be made, a NICS check must be conducted by a dealer on the purchaser. While a dealer is not required to facilitate a private sale, if a dealer chooses to do so, he or she must create and maintain records relating to private sales to prove that the background checks were conducted. These records may be inspected by a police officer and are not subject to public disclosure under the FOIL provisions. The Safe Act provides that a dealer may charge up to $10 for facilitating these private transactions"
"3. Potential Charges
GBL Section 898 (6) / Unlawful Private Sale of a Firearm, Rifle or Shotgun.
A knowing violation of these new provisions of the General Business Law, regulating the private sale of firearms, is a class A misdemeanor. The enforceable subdivision is subdivision (6) of GBL section 898."