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AR barrel/flash hider question


techmike
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The accuracy on my AR kept getting worse, so I took it all apart, and when I removed the flash hider and crush washer, I found random metal deposits on the muzzle crown. (see pic) There was an internal gap between the an internal ridge in the flash hider and the crown. (Due to the crush washer?) I am assuming that the gap was trapping hot gas/lead/copper and plating it on the crown, and that the deposits were causing my accuracy issue. The deposits came off easy using a lathe. So I bought a new flash hider today, and it tightens down and indexes correctly without any crush or peel washers.

Question: Do I really need a peel/crush washer? I had planned on just installing it with thread locker, since it indexes correctly. The barrel is a Model 1 Sales, crown is cut at 90 degrees.

Thanks!

TM

post-10-14412437861_thumb.jpg

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Put it back together WITH the crush washer in place. The crush washer is there to keep the hot metals from reaching the threads. If allowed to flow into the threads you will find it near impossible to remove the flash hider next time as it will have been soldered in place. It will take a lot of heat to remove it if this happens... read torch. The high pressures will push the hot metal into the area no mater how close the tolerances, proper indexing or not. You might even want to pick up a new crush washer to have on hand for use after cleaning it next time.

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Went to the range Sunday, and glad to say the AR is getting groups at 100 yds again. I believe the crush washer was the cause of the muzzle deposits and accuracy issues - I think it kept the barrel from threading fully into the flash hider. With the barrel all the way into the new flash hider, I have also noted a drastic decrease in muzzle report. Please see attached picture of autopsied flash hider.

4058_208c5ef8130b3e824d0aea555fc65ac63add5b04.pdf

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  • 3 months later...

So I bought a new flash hider today, and it tightens down and indexes correctly without any crush or peel washers.

Question: Do I really need a peel/crush washer?

Did it tighten down, with no washers, to 20lb/ft?  If the answer is no, then you need something in there to hit that torque setting.

There's 540-degrees of rotation in a "proper" crush washer.  Even it you hit it with nothing, you can get a full 360 with a crush washer.  Plus another 1/2 rotation.

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Put it back together WITH the crush washer in place. The crush washer is there to keep the hot metals from reaching the threads. If allowed to flow into the threads you will find it near impossible to remove the flash hider next time as it will have been soldered in place. It will take a lot of heat to remove it if this happens... read torch. The high pressures will push the hot metal into the area no mater how close the tolerances, proper indexing or not. You might even want to pick up a new crush washer to have on hand for use after cleaning it next time.

HOGWASH! ::)

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