Give him an itemized list of what is wrong with the Beretta and show him how it differs from the ad- tell him you would like him to cover the items that were missing/damaged or at least split the cost. Tell him you can sell the delay box to offset the cost, or he can make good on the car and then you will send it.
Make sure you pdf the documentation on what was wrong and email it to him. See what he says.
He deserves the box because you agreed to send it. You deserve what he advertised and what reasonably couldnt be expected to be caught on initial examination.