....as mentioned, this was minted in San Francisco in 1967. ...but yes, things have come out of SF, Denver, and Phila. over the past 53 years.
I understand, but SF did not have the minting history of Philadelphia. I was simply pointing out the US has a LONG tradition of made to order "items" for collectors, probably predating the 1804 silver dollar.
I've worked with enough pressmen and tool & die machinists who needed a quick fix to last them until the end of a shift or a day when they could take the tool down for permanent corrective action. I can recall instances where we would capitalize on the existence of one or more vacant threaded holes in a problem area of the tool that permitted such a fix to be installed and function for the required time. As such, it is not hard for me to visualize this screw vibrating out of such an arrangement, and finding its way into the coining chamber. Probable? . . . no. A remote possibility? . . . Of course.
The screw bears all the signs of a piece that has seen major fatigue up to the point of failure. Bet that die set caught hell. It's impressive to see the details stamped onto the screw itself. Perhaps it is a soft stainless steel screw. Very cool.