As an aside, I have a friend who works for the USPS. He tells me it's better to have delivery confirm and no insurance than insurance and no delivery confirm.
Amen to that. Sold an H&K part through a gun related site, guy sends the funds and I paid the extra coins for DC. About 5 days later, USPS website says it has been delivered. The NEXT day I get an e-mail from the buyer claiming it has not been delivered. I write back and tell him it was. Get another e-mail and the same thing: "Where is the bolt?". At that point I send him the DC number and the URL for looking it up on the USPS website. Three days later the buyer e-mails me and admits he got the part..... Was he trying to scam me? I don't know but I do know if I hadn't gotten DC, it was going to get ugly, based on the "tone" of his first two e-mails.
In all fairness, perhaps his life partner got it and stashed it in a closet or a car trunk but it sure felt like a scam in the making. On that board, just as here one can post about how deals went down so it would have been his word against mine without the DC to go by. I have seen several people on that particular board who can no longer sell items due to their past behavior, whether grossly misrepresented items, slow shipping or not shipping at all.