Was thinking about earlier comments in this thread. I don't think the SIN was to allow police to ID and return to you - it was for you to ID as your stuff. You filed a report that it was stolen - here is what it looks like. Many rifles, like Cooey, did not have serial number. So engraving SIN or Regimental number or whatever was pretty unique way to identify an item as belonging to you - in Op's case, the scope, the mount, the rifle, etc. Regarding current concern about use of SIN: When I went to Tech in 1980's / 1990's, (Moose Jaw, Sask, Saskatchewan Institute of Applied Arts and Science) our SIN was our student number - had to rattle it off if you wanted to pick up marks, or whatever. May not be what it is thought of today, but not that many years ago, was a very commonly used number to associate with you. I actually filled out forms, in class, and received mine as handout from high school teacher in high school - perhaps 1970?