Dwight,
This is my 1911 with added holdopen and no proof on stamp on the side of the frame.
the pin was machined very nicely to match the rail, but under the rail some missed a punch or something.
The holdopen itself is stamped with the last two of ser # and crown proof
http://boards.rennlist.com/lfupload/Rightsidehold.jpg
http://boards.rennlist.com/lfupload/HOLDOPEN2.jpg
Hope this is some help to you
Jim