Going to show some ignorance unfortunately, but I've got a question I'm sure you guys can help me out with. I see the serial numbers blotted out in pics of firearms for sale but never truly understood why. Now I've got a friend asking me if he should release the serial number of a pistol he owns to a potential buyer. Buyer says he wants to "make sure the pistol is clean" which it is of course. I've never dealt with this and I'm stumped as to what to tell him. Thanks in advance !