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Discussion Starter · #1 ·
I read here in a post from another user that they tried an o-ring on the barrel to keep the thread protector from coming loose. The size suggested was 7/16 ID x 9/16 OD x 1/16 wide. I ran out to Home Depot and picked some and tried them out. They will certainly keep the thread protector on, but the thread protector will not seat properly.



The thread protector seats against the muzzle end of the barrel, not the shoulder of the threads. You can see the large gap between where the thread protector is supposed to seat against the muzzle and the barrel itself. You can also see the o-ring bulging out behind the thread protector.

I did some looking around and found Viton o-rings. The have better heat resistance (400 degrees vs 250 degrees for the standard Buna-N o-rings). I settled on 12mm ID x 1.5mm wide (15mm OD)



A little bit of oil around the inside of the thread protector and the o-ring will be compressed under the thread protector allowing it to completely seat against the muzzle. Took it out for a spin and 170 rounds later the thread protector was still tight.



You can get them at http://www.mcmaster.com/#9263k296/=e6g2fv for $6.56/25 and about $5 shipping.
 

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BlindGuyShooting said:
It the thread protector coming loose a common issue
Kind of common with all threaded barrels. Silencers will do the same with use and need to be checked.
 

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I think it would be a good idea for all manufacturer's to send some rings like this with the guns/suppressors to help prevent the protector/suppressor from coming loose.
 
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Discussion Starter · #7 ·
A little bit of oil spread or brushed on to the o-ring is probably necessary as well, especially the first time you put it on. After the thread protector has been on for a while the o-ring compresses a bit and will hold that shape for a while so the thread protector gets easier to remove and put back on, but the o-ring will take its original shape again if the thread protector is left off for too long. I don't imagine anybody is going to be taking the thread protector off and putting it back on again repeatedly, so the o-ring should last quite a while.

Also, the o-ring will need to come off to get the barrel out. I tried leaving it on but it just barely won't fit, the o-ring ended up rolling down the threads and almost completely off, so you might as well just take it off.

I would think you could leave this o-ring on when using a suppressor to help keep it tight as well, but since the o-ring would be compressed outwards when the suppressor is on I'd make sure to put some oil on it before putting the thread protector back on, or letting it sit for a while so the o-ring can flatten back out.
 

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Oring

Often I fire quickly enough, and enough rounds to have the barrel get quite hot. Will the oring not melt? Has anyone put the very mild locktite on the threads? Also, perhaps it's my imagination, but I "think" my FN is a tiny bit more accurate AFTER the thread cover loosens in firing.
 

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I just get a roll of teflon thread tape. it works for suppressors and thread protectors. Also cheap.
 

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This is an old thread but I was wondering a couple of things... now that you all have been using these for some time, does the heat cause a problem with the o ring melting? Is teflon thread tape a better choice? I would go through o rings like crazy as I clean my weapon after every trip to the range.
 

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O=ring works well for me. It does have to be removed when you remove the barrel for cleaning, so it wears after several on/off cycles. In the past year of once a month shooting, I have used a total of 3 O-rings.
 
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