I am not a lawyer, but I would think that no transfer has taken place if the buyer refuses to accept the merchandise, especially if there is any documentation of the customary 3-day approval period. I have been told by my FFL that he is required to log received guns withn 24 hours of receipt, whether or not I actually accept the gun. Logging the gun for BATF purposes is different from transferring the gun to me as the buyer. From a contractual standpoint, using the old offer/consideration/acceptance model, is there an actual transaction or just a negotiation that does not result in an actual sale?