How do I remove my RRA NM Tube

[hylander]

I want to remove replace my NM FF tube with a standard
round FF tube.
How do I remove the NM tube ?

[killshot44]

A round, smooth lock-nut bears on the barrel extension collar and pushes it against the receiver. The sleeve is threaded into the lock nut and tightened to a spec of 35 ft-lbs.

Call up Sacramento Black Rifle, I'd bet they have the tool for it and would do it in no time. They may even have the FF tube you want.