How do you keep your direct thread suppressor from backing off?


Feb 9, 2013
Knoxville, TN
Pretty simple subject...I shot my 308 AR with my direct thread SAS Arbiter this past weekend to get some test hunting loads zeroed and chronographed. They did great, but at the end of the session (total of 15 rounds) the accuracy went a little haywire. After the last shot was done, I checked the suppressor and it had backed off just enough to need a small nudge to tighten up. It hadn't let go enough to get a baffle strike, but it did throw off the harmonics enough to send the bullet somewhere other than where it was being aimed by a couple of inches. I'd like to add some kind of silicone washer between the rifle muzzle shoulder and the suppressor, but I don't know of anything that can resist the heat created by shooting suppressed.

So what do you use to keep the suppressor from backing out for direct thread? Getting another mount and proclaiming the benefits of a QD attachment are not helpful.
My problem with direct thread is usually getting them off. Maybe de-grease the threads before your next outing. Invest in a strap wrench and it'll help you tighten it a bit more when installing and help when carbon buildup makes it a bit hard to get off.
For this application yes. If using it as a thread sealant no. It is merely acting as a vibration dampener. If it gets too hot, it melts and acts like glue.
Main thing is make sure you don't obstruct the bore, and stop short enough that it does not push up between your barrel shoulder and mount. 2 or 3 wraps should suffice. Too much and the muzzle device will start pushing it against your shoulder.
15 rounds before loosening to the point of being detrimental to accuracy is... unacceptable. What do your threads look like? Strap wrench that thing on tighter, because that really shouldn't be a thing.
How much of a shoulder does your can have to index on? It needs a decent amount to provide the friction to keep it in place.

If it keeps shooting loose, it might be time to send the can to ECCO to have some sort of muzzle brake adaptor put on.
Hmm. On mine, I used the wrench to tighten the direct thread mount to the can. Then screw it on the muzzle threads, finishing it off with a good snug hand tightening.

Usually takes a little bit of force to remove it after shooting a while.

Maybe try degreasing your threads and use a strap wrench.
So what do you use to keep the suppressor from backing out for direct thread?

I make sure it is properly snugged down before I start. I run two direct thread suppressors. I crank them down by hand and I am usually good to go for a getting zeroed and a night of hunting.

I will also take opportunities (when I think about it) to check and retighten as necessary. Usually isn't an issue. However, direct thread suppressors generally are not a set and forget attachment unless you use a threadlocker (see above), or until you get it carbon-frozen to the rifle. At that point, it takes penetrating oil and a torch to get it loose...which is great until you want to take it off, LOL.
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For my handguns, Ive been using Viton "O" rings and they have been working out well. The can might loosen up a little over a couple of hundred rounds, but seems like its considerably less.

My rifles use a ratchet mount, so I cant say there, but they might be worth a try there too.
Don't use any spacer or washer, I tried this and it is a no-go! You will likely end up with the can off-axis. When I tried it, I got baffle strikes and the rounds went off paper at 25 yards, with a .22 rifle.
Try a strap wrench first, if that doesn't solve the issue then you have a mechanical issue with how the two components "mate."
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My Ruger Mark III threaded pistol came with a very thin wavy washer. Of course I quickly lost it and haven't been able to find a replacement since. Regular wave washers don't have the right diameter and opening commercially.
Teflon or a small oring. I’ve also successfully used dental rubber bands (from braces) to tighten up muzzle thread and ar upper/lower connections. You don’t want an oring big enough to get pinched between the muzzle shoulder and the suppressor… you want one that rides behind the barrel threads only slightly wider that the threads OD so it fits inside the suppressor threads just snug enough to damper vibrations
So what do you use to keep the suppressor from backing out for direct thread?

I only have one that never seemed to stay tight (probably from people holding on to it while firing), I welded on what amounts to a split set collar to lock it in place.


No, no flats on the suppressor.

This can be a problem for removal or taking apart some cans, if they get too dirty. You can still get a good grip on them, using the same concept as above.

Like this, bore the ID of aluminum to match the OD of the part, then cut a slot in it, so as its clamped the ID grips the OD tight, without damage to the OD.

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I do not shoot my cans for very many rounds without checking them, out of habit, Got single shots, bolts and ARs with cans but I have no need to shoot more than a couple of rounds between check hand twists.