Two Differnt Sizes!
If you bought the surplus Hartwells from ACS, you might be surprised (as I was), that there are two different "depths" of Hartwell - one is stamped ".040", and the other is ".091". ACS was unaware of this, and they only have one part number for them both. When I ordered two, I got one of each depth! I called and chatted with them, and determined that the depth I wanted was .091, and they sent me another one....for free!
Check to see if yours are stamped on the back with a depth....
Paul Dye