Yesterday, I noticed that my AR10 flash suppressor begun to unscrew off of the barrel.  The threading was done in late 2004 by ADCO, and the flash supressor indexed correctly without any washer.  When I went to tighten the thing, I could actually crank it past the point at which it was indexed previously by perhaps 10 degrees.  This whole thing raises a couple of questions:

1.  What's my best option?  I could take it to the point where it's indexed and use plenty of thread lock, or add a washer.  My issue with this second option is that it would no doubt put the flash suppressor out further on the threading than it was without a washer.

2.  What holds these things in place? This is the first time I've ever actually examined a threaded barrel with the flash supressor loose.  It seems like pure friction is just not enough.

That was my first thought as well, but I'm somewhat curious and perhaps concerned that ADCO originally did it without one.

ETA: Also, where might I find an AR10 peel washer?

Is is a Vortex?  They are the only ones I know of that don't use a washer.

It's an Armalite A2 flash supressor.

Love, like the love a man has for a fine cigar

You should be able to use some peel washers.I like em better than crushwashers.

My thought exactly. Does anyone know who sells AR10 peel washers?