I was shooting this weekend, when I noticed my ARMS #40 was about to fall off. Which is my fault, not the sight. I keep it in folded position so I didn't notice it was coming loose. Honestly, I probably didn't torque the nut down when I first installed it. I rarely use it, even though it is my favorite BUIS.
I found the cross bolt, and the clamp, but I am missing the nut. I am not sure how hard that will be to come by. Any advise in that department will help. I just emailed ARMS and look forward to their response. I tried finding it with a magnet to no avail.
What is the steel cable looking thing in the picture below? What is it's function? I don't remember seeing it on my ARMS #40, and it isn't present now. I am not sure if something else fell off.