Pretty sure I'm running something similar on one of my ARs, I know it's a Troy, but don't recall needing a specific barrel nut....
If I can figure this out, I have an AR I could use it on.....
I've seen your Troy rail mentioned a few times, I have one that I think is similar, but don't recall needing a different barrel nut, is that specific to the one you've got posted (Sorry, I'm dumb when it comes to some of the forearm stuff)
Hitting up the KKlub operators for their critique on a low-cost chest rig, since some of y'all never leave the KK forum ;D
Critique this, please ---> https://www.southeasttraders.com/threads/recent-chest-rig-purchase-for-critique.24663/