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9/22/2017 12:11:25 AM
Posted: 9/15/2005 9:27:25 PM EDT
Hello,
I finally put my first AR together from seperate parts. All major compoonents are RRA. I got the threaded RRA barrel and bought the Birdcage flash hider from RRA seperately. I also have the crush washer. I know that the slits on the flash hider supposed to face up when installed, but when I hand tighten the flash hider, there is still a 1/2 turn necessary for the slits to face up.

I use an open ended wrench to compress the crush washer but it seems pretty hard. My question is, how tight this supposed to be? I don't want to damage anything.

Thanks for the information.

BTZ28
Link Posted: 9/15/2005 10:09:30 PM EDT
Just a minor correction.
I believe that you have an A2 compensator if there are only vents on one side.
The A1 flash hider is usually called a birdcage as it has 6 vents, equally spaced all the way around the outtside and it does NOT need to be aligned to face any direction.

As for your A2 comp, just torque it on there until the vents face upward.
You should not be fully flattening the crush washer.
Some of the cone shape will still be visible once you are indexed properly.
The spec actually calls for the center vent to be within 1/2 the width of the vent of straight up.
Most people put them much closer to straight up than that.

I don't like how tight the comps with a crush washer end up either...

Randall Rausch
www.ar15barrels.com
Link Posted: 9/15/2005 11:17:05 PM EDT
Link Posted: 9/16/2005 3:03:47 AM EDT
not all of them crush when suppose to, there are stubborn ones

s­ome grind the washer down a bit, some pre-crush it in a vise. i have never had any problems with tighten, loosen and tighten a few times till it gets to where i need it to be.
Link Posted: 9/16/2005 3:11:36 AM EDT
[Last Edit: 9/16/2005 3:12:29 AM EDT by von_landstuhl]

Originally Posted By BTZ28:
I use an open ended wrench to compress the crush washer but it seems pretty hard.



A few weeks ago , I did my first birdcage install using Bushmaster parts. I used a crescent wrench and mine didn't line up at first either. I actually took it off twice to see if there were two sets of threads. ;)

Finally, I decided to just take it one more turn around. It was hard, but I went slow, giving the washer time to compress before torqueing it a bit more. I've read of crush washers that don't want to compress, so I guess I got one of those.

BTW, I was using a vice block around the upper and lower, but I would have felt more comfortable with something around the front sight.
Link Posted: 9/17/2005 6:56:08 PM EDT
Do NOT use an action block when twisting on (or off) a flash hider (or brake, or comp). This puts stress on the barrel alignment pin and the corresponding slot in the receiver. It is possible to twist the barrel, denting the pin into the soft aluminum receiver and thus canting the sight to one side.

Use barrel vise jaws for installing or removing muzzled devices.

Use action blocks when installing and removing barrels from the receiver.
Link Posted: 9/17/2005 7:05:58 PM EDT
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