Stangfish, yes, it is green.
Bradley, what I have done is set the head space. then thread the nut forward as far as it will go then drop one drop of loctite, maybe another at the opposite side. The loctite dont go too far and all you have to do is replace the lock nut back where it was before which will take a few seconds... Or you can just pin it. I think both process will work the same. Good luck.