The outer barrel is fixed to the RIS and is plastic and not removable. For god sake at lease make it metal! Why!!!???? G&G WHY!!??
To update my original comment I have spoken with the techs at G&G (US division) and they were nice enough to grab one of these 100Y models and actually attempt to take the flash hider off while I was on the phone. After about 15 minutes on hold, I was told that is was not removable without risking cracking the outer barrel. If you go the G&G website, look at the Exploded View and zoom in, you will notice that there are threads on the plastic outer barrel. I can only come to the conclusion that it is strongly glued at very least, and to risky to be removed safely without totally destroying the outer barrel. I have already ordered mine and will update this forum as soon as I get it and have a concrete answer.