Marney, see pic FAR RIGHT ON BOTTOM OF STOCK LUG, on models without Stock Lugs I put it inside the bottom of the frame/mag well. You have to take the magazine out to see it! On guns I only do parts on I dont mark them as most of the gun is either original or don e by someone else. I do add them to full reworks that I do.
http://boards.rennlist.com/upload/Thormark.jpg