Quote Originally Posted by INLAND44 View Post
Auto Ordnance for IBM. Some of them had heat-treating problems. The 'X' marks the accepted ones. There's something else about the 'X' but it escapes me at the moment.
So the ones without the X weren't accepted? Strange because a whole bunch of AOB bolts don't have an X on them.[COLOR="Silver"][COLOR="Silver"][COLOR="Silver"]

---------- Post added at 09:53 PM ---------- Previous post was at 09:51 PM ----------
Quote Originally Posted by Phrogpilot View Post
Actually, the "X" means it was used for interchangeability tests...
No it doesn't. It means they bolt doesn't have all the design revisions incorporated into the round bolt design. If you can find an ordnance document that says bolts marked with an X 1/2" rear of the locking lug were used in interchangeability tests post it. In the mean time you might want to read MAJ Nielsen's Memorandum dtd, 4 September 1944.