I thought "top secret" meant what he was actually running last year at KC. Scorpion upper? MCX upper? MP5 upper? something actually useful with modern mags and drums.....
My buddy Zack had a solid run:
https://youtu.be/khzRJK4qhss
the few hours I watched there was a bunch of good runs. Twzadams (Cory) had a great run despite some tech difficulties. Thankfully Richard Lage was able to help him out.
I think the hook in the middle is for a 1 piece pin that has a groove in the center. The hook is actually supposed to be pointing the other way IIRC. I think I grabbed mine and pulled it when it was off the receiver like that and it flipped back but wouldn't flip forward.