"three snugs" barrel install method?

[Jay Cunningham]

I know the proper torque range for barrel nut installation. I have also read in several different places about a method that involves snugging up and then backing off three times, and moving one hole past the final snug up.

So I am asking those *with experience* - does this method achieve a good result?

[Iraqgunz]

J,

This is done in order to work the threads and get a better seat. On the third attempt is when I do the final lock down and line everything up. I don't loosen it to make it line up, but rather tighten it a little more than the book calls for if necessary. I also use Loctite C5-A anti-seize.


I know the proper torque range for barrel nut installation. I have also read in several different places about a method that involves snugging up and then backing off three times, and moving one hole past the final snug up.

So I am asking those *with experience* - does this method achieve a good result?

[Jay Cunningham]

So you lube the threads with moly grease, work the nut three times and then forward to line up with the next hole. Have you ever double-checked the torque spec on this? Do you know whereabouts what kind of value range this delivers?

[VLODPG]

I am going to be mounting a barrel in a Vltor VIS upper & the wrench that comes with it says it is a one time use only part.

Any insite on the wrench, is it a one time use part because it won't hold up to multiple torquing or just because they enclose one with each VIS?

[Iraqgunz]

I work the threads first 2 times and then apply the anti-seize and tighten. I can't tell you about the torque value as I never use a torque wrench unless someone specifically says I need to. Usually when you beging to tighten you will end up with a spline of the nut just to the left of the receiver hole and you will be just slightly off mark. Then I apply the wrench and begin to apply steady and slow pressure until it lines up. More often than not I will hit the mark.

I had a few instances where I actually had to use a different barrel nut.


So you lube the threads with moly grease, work the nut three times and then forward to line up with the next hole. Have you ever double-checked the torque spec on this? Do you know whereabouts what kind of value range this delivers?

[Failure2Stop]

What I was taught was this-

Set torque wrench for just above the minimum 35 ft lbs and tighten to torque spec.

Set torque wrench for 80 ft lbs and loosen and tighten 3X to next hole. If you reach the high torque without getting to the next hole get a different barrel nut and start again.

This is simply what I was taught and have done a few times. I have no strong feelings about it what-so-ever, though it makes sense to my pea-brain.

[Quib]

I’ve found that sometimes it takes more than three tighten/loosen sequences to align the barrel nut, and view the 3X rule as a minimum.

My procedure:

- Liberally apply grease to the barrel nut threads and the receiver threads.
- Tighten the barrel nut utilizing my DPMS Armorers Wrench (1X).
- Observe barrel nut alignment. This initial tightening should give me a rough estimate of how far the barrel nut alignment is off.
- Loosen barrel nut.
- Tighten the barrel nut (2X).
- Observe barrel nut alignment and compare movement to first tightening.
- Loosen barrel nut.
- Tighten the barrel nut (3X).
- Observe barrel nut alignment and compare movement to second tightening.

At this point there should be a noticeable movement in the barrel nut towards alignment compared to the first tightening attempt.

- Tighten the barrel nut (4X).
- Observe barrel nut alignment and compare movement to third tightening.

At this point if alignment has been reached I’ll consider the barrel nut tight and install the gas tube. If the barrel nut alignment is still off, then I will continue the tighten/loosen sequence until alignment is achieved.

This procedure has not failed me yet, or resulted in a loose barrel.

[Jay Cunningham]

Good info.

[Robb Jensen]

Torque at least three times with plenty of moly grease on the threads. Some barrel nuts require a lot of torque to align. With these you may need to torque a lot of times. I've had to torque, loosen and re-torque some bbl nuts 50+ times adding a little more torque each time to get them to torque under 80ft lbs. With standard bbl nuts I'd just try another bbl nut, when it's a proprietary nut I don't have a choice nor spare bbl nuts to try.

This is one of the genius inventions with the DD Lite Rail barrel nuts. You can do the three torques and the just make the final torque whatever you want since barrel nut gas tube hole alignment doesn't matter since the gas tube passes over the barrel nut not through it. I set my torque wrench for 70ft lbs for DD Lite/RISII/Omega X bbl nuts.

[SHIVAN]

This is one of the genius inventions with the DD Lite Rail barrel nuts. You can do the three torques and the just make the final torque whatever you want since barrel nut gas tube hole alignment doesn't matter since the gas tube passes over the barrel nut not through it. I set my torque wrench for 70ft lbs for DD Lite/RISII/Omega X bbl nuts.

Yep, SWS does similar with his barrel nut. I love the no gas tube infringement installs.

I also use the three or four snugs and "it's good" method of install. So far, no issues.

[Bubba FAL]

FWIW - The three snugs method comes straight out of the USMC M16A2 Maintenance manual.

I snug to 30ft/lbs 3x, then tighten to align to the next gas tube slot. Though I've only installed 6 AR barrels, I've not had a problem with this procedure.

Always, always, use anti-seize on the threads, even if test-fitting. Steel nut on aluminum threads is bad ju-ju if not lubed, and a good way to learn about galling. A few cents worth of anti-seize is cheap insurance against a ruined upper.

[scottryan]

Torque specs on these I have come to realize are a waste of time.

Wide variations in factory torques I have noticed over the years. If it is tight enough and it is aligned it is fine.

All a torque wrench does if increase the chances of pulling the wrench off the barrel nut and bending teeth.

[seb5]

When I started playing/building AR's I bought all my tools, including a snap on torque wrench. The wrench hasn't been used for a few years. I apply anti sieze, snug them up 3 times and tighten to next slot. As noted above on occasion you have to tighten/loosen more than 3 times. With the DD nuts I tighten/loosen 3times then just snug them up and go. Over the years I've kind of got a feel for how tight is tight enough and go with it. I suppose I should get the torque wrench out for the DD type nuts but haven't had any issues without it.

[ST911]

Moly-B on the threads, then the previously mentioned 3x method, tightening to alignment on the last. Fourth time, if necessary. No torque wrench unless required.

[J Krammes]

What type of anit-seize are you guys using? Does the type matter?

Jeremy

[Jay Cunningham]

I had a question about this myself. Would there be any possible, logical reason why I couldn't use nickel-graphite anti-seize?

[seb5]

I believe I use the loc-tite brand from Brownells.

[crazymoose]

I had a question about this myself. Would there be any possible, logical reason why I couldn't use nickel-graphite anti-seize?

Can't tell you the science behind it, but I've been told that graphite lubes will facilitate galvanic corrosion. I use the molybdenum disulfide paste that comes in the little white jar.

[EzGoingKev]

What type of anit-seize are you guys using? Does the type matter?

Jeremy
A friend of mine used to work at a Mercedes Benz dealer and liberated several tubes of their anti-seize and I like to use that for all kinds of things.

The anti-seize sold by Permatex, Loctite, whoever dries out after a period of time. The MB uses a molly based grease in their anti-seize and it doesn't dry out. You can really feel the difference when you thread a nut on or install a bolt in something.

[Sparky5019]

I just had to get a new barrel nut from LaRue as the one that came with the HG was <35 at 1st hole alignment and would not move any farther at 80. The new nut fixed it. I use Brownells barrel paste for the threads and used a technique similar to GotM4's and it went to the next hole around 80 and lined up perfectly!

Sparky:D

[bnanaphone]

In assambling my AR, I read all I cojld on this subject and followed the processes described above. I used anti-sieze on threads, did the tighten/loosen 3x and then went for it. I was installing a Larue HG + bbl nut and to get proper alignment for gas tube, I tightened nut to 81 ft/lbs. Will this be an issue? Should I re-do the whole thing? Thanks.

[Robb Jensen]

In assambling my AR, I read all I cojld on this subject and followed the processes described above. I used anti-sieze on threads, did the tighten/loosen 3x and then went for it. I was installing a Larue HG + bbl nut and to get proper alignment for gas tube, I tightened nut to 81 ft/lbs. Will this be an issue? Should I re-do the whole thing? Thanks.

Should be fine most torque wrenches are off 1-4% anyway. 1lb is nothing.

[bnanaphone]

Thanks for the info, I really didn't want to re-do that Larue Rail again anyway.

[C4IGrant]

J,

This is done in order to work the threads and get a better seat. On the third attempt is when I do the final lock down and line everything up. I don't loosen it to make it line up, but rather tighten it a little more than the book calls for if necessary. I also use Loctite C5-A anti-seize.



This is exactly how we do it right down to the C5. ;)

I also use an alignment pin (that is the size of a gas tube) and check that it is sitting evenly on the barrel nut (not more to one side or the other).







C4

[C4IGrant]

I am going to be mounting a barrel in a Vltor VIS upper & the wrench that comes with it says it is a one time use only part.

Any insite on the wrench, is it a one time use part because it won't hold up to multiple torquing or just because they enclose one with each VIS?


You can use the wrench more than once (FYI).


C4

[C4IGrant]

I think a lot of times people use WAY too much torque when installing barrel nuts. I am also almost positive that excessive torque can be a detriment to the weapons accuracy.

If at all possible I really like to stay between 60-70. If the gun has an anti-rotational system (like the DD and LT rails), I like to keep the torque setting even lower.



C4

[rob_s]

I have installed probably a couple dozen barrels, and had occasion to mess with barrel nuts of one form or another a couple dozen more times. Yesterday was the first time I'd encountered one that wouldn't line up at a torque value I was happy with. I cannot physically get it any tighter and the gas tube is binding enough that the carrier won't drop in as it hits on the key. If I loosen it to the next gap it is not tight enough for my liking given that I'm using a FF tube that attaches to the stock nut. I also buggered up the teeth a bit when the DPMS wrench slipped off the nut.

I'm going to tear the whole thing apart again and grind off that tooth with the Dremel.

Wishing I had not just said "eh, **** it, it's only rubbing a little" and had checked the carrier issue before installing, and loc-titing, the FF tube. :mad:

[C4IGrant]

I have installed probably a couple dozen barrels, and had occasion to mess with barrel nuts of one form or another a couple dozen more times. Yesterday was the first time I'd encountered one that wouldn't line up at a torque value I was happy with. I cannot physically get it any tighter and the gas tube is binding enough that the carrier won't drop in as it hits on the key. If I loosen it to the next gap it is not tight enough for my liking given that I'm using a FF tube that attaches to the stock nut. I also buggered up the teeth a bit when the DPMS wrench slipped off the nut.

I'm going to tear the whole thing apart again and grind off that tooth with the Dremel.

Wishing I had not just said "eh, **** it, it's only rubbing a little" and had checked the carrier issue before installing, and loc-titing, the FF tube. :mad:

Ya, I see these once in awhile.

Just get another delta ring assembly and try again.

When you are running into high torque values with the DPMS wrench, have someone pull back on the Delta Ring (to remove stress) and you will be a lot less likely to slip off the barrel nut teeth.


C4

[rob_s]

Removed the Delta ring, snap ring, and spring.