On my 906C there's a small hex bolt on a thread that you can see through a slot in underside of the handguard, close to the receiver. I think you just loosen that off to detach the handguard from the top receiver.
And there's a small hex bolt at the front end of the handguard that also needs undoing.
I've not had to take my handguard off, so maybe I've missed something! Also - I can access the grub screw without doing that (which is nice) - I'll be needing to do that as I've got a suppressor on the way.
Edit...
Pic of the two things I'm talking about...
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Well wouldn't you believe it. The suppressor I was talking about is a Novritsch one that I ordered on Black Friday... but a little before that I'd ordered a cheapo one from AliExpress, and it's just turned up! So I had good reason to take the flash hider off mine.
I had no problem with the grub screw, and no problem with the flash hider either. No thread lock goo found in mine.
I fitted the suppressor and managed to chew up some of the thread as it's quite fine and very soft and my first attempt wasn't quite done right... so do take care when fitting your tracer (of course, if it's a reputable make it might only go on 'properly'). And I noticed when trying the flash hider back on my slightly mangled thread that it's (now?) quite loose, so that grub screw is important - don't lose it!
Anyway the result is rather nice, though the finish is a little too shiny, i might rough it up with a brillo pad or some polishing paper. It'll get replaced anyway when my Novritsch modular one turns up, complete with camo cover for a different look... but not bad for less than a tenner!
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