As long as you have the flash hider tight and the center slot of the flash hider is in line wth the front sight base you are good to go. All crush washers will have a slight outward flange to them. You definitely do not want to over-tighten it.
Originally Posted by Flash Point
First post and a question about crush washers. I began shooting ARs in 2002 but just recently completed my first build from the ground up (including barrel installation). The finished product was a M16A4 clone that shoots just fine. The only snag I ran into was with the crush washer between the barrel and flashhider (easiest task - go figure). Should the washer be totally flat after tightening? Right now the A2 cage is properly aligned, but the washer has a slight angle to it. It doesn't look as if another full turn is possible. I've tried rotating the washer and starting the hider at different points on the threads with the same result. Can these washer be "crushed" far enough to get another turn on the threads?