Ok, I moved from my laptop to the desktop and big monitor. Only thing I see is the circle (pin?) on the safety lug. I guess I can't see the forest for the trees. That means nothing to me and my books have been moved to the new house so I can't look it up if it is indeed the anomaly. For what it is worth, I passed on this one when I first looked at it also. I only noticed the features I mentioned after you posted the thread and it took me three passes to notice the checkered bolt.

It ain't ignorance that does the most damage, it's knowing so derned much that ain't so! J. Billings