Fernando,
Thank you for your research. Yes it is a very curious piece and I did find the thread from 2000 that you mention (
http://www.thefiringline.com/forums/...ad.php?t=45496). The woman (Lisa) gives her e-mail and I sent her a message, unfortunately the message bounced back.
It seems like Lisa never got any replies on her original post. Clearly this group is doing better.
The fact that she had the same SC1913 mark makes it seem more likely to me that is a year or contract stamp. The person who sold mine thought that was the serial number.
There are 2 numbers which appear in several places on my gun, 39 and 316 (see picture below). I am guessing that 316 is the serial number and 39 some sort of assembly number.
You have to love a puzzle. Thanks to all for the interest. I hope we figure out the crown and keys!
Cheers,
Marcus