I can't search far back enough but I remember a thread here where we were discussing the torque limit on the barrel nut and it was mentioned that around 80-125 ft/lbs was okay.

I believe it was also mentnioned that Colt was the source of these numbers.

Can anyone here comfirm this and possibly post a link to that thread?

Thanks!

80 lb-ft is called out in the USMC manual as the maximum to get the gas tube alignment. You can veiw it from the home page here I think. There is a recent thread that a fella wants to know which manual is best.... Might be able to search it, 2 different links to the manual online were posted.

[url=http://www.jobrelatedstuff.com/content/books/TM9-1005-319-23.pdf]TM 9-1005-319-23[/url]
2.6MB

I'm at work so I don't have my TM handy but 80 ft/lbs is what sticks in my mind. It's rare to reach 80 w/o lining up the teeth for the gas tube. If that does happen loosen the nut and retighten, repeat until the nut lines up properly. Unless, like some of us, you have a drawer full of barrel nuts. Use lots of grease and watch the engagement between your wrench and the nut. The teeth tend to break off around 100 ft/lbs so it's difficult to get the nut too tight. Torque limits, in this case, are designed to prevent the assembler from doing harm to himself (wrench slips) his tools (tool snaps) and the parts (teeth break, threads strip). Tight is tight, loose is loose. Worry about the minimum, the rest will fall in place.

45lbs

From
Page 3-43
TM 9-1005-319-23&P
C6
OCT98

[center][b]CAUTION[/b][/center]
"Do not torque over 80 ft-lb (108 N-m) while tightening the barrel nut assembly to the next hole, to allow for proper alignment of the gas tube."

Thanks guys![:D]

Thanks for asking about this Yojimbo.  Tweak, sorry, I only have 1 barrel nut.[:)]

I did the whole lube, retighten, etc. thing 20 times and I wasn't getting anywhere so I said screw it and went ft/lb by ft/lb 'til I lined up at 84ft/lbs.  I seriously doubt I harmed a thing, firearm operates fine, and I didn't feel or hear anything marring, etc. during the tightening.  Haven't lost a moments sleep over it.

As long as it is getting harder to move the wrench to tighten, you are OK.  If suddenly it gets easier... THEN you have problems!

[lolabove]

Yeah, I never get used to the horrible metallic screech when the nut strips. [:D]

I'd bet ya that if you take the barrel off and re install it you won't need to use as much pressure. But why take it off? On is on.

For the rest of ya, this is why we lube the hlel out of the mating surfaces and threads on the upper and barrel nut. The threads can stick without lube and WILL if a lot of tension is applied. Then they're a joy to remove and if you really tighten one on you WILL have to remove it. That's the way it works.

The minimum barrel torque is 30 ft/lb and maximum is 80 ft/lb.  I like to torque 2 to 3 ft/lbs more just to make sure.  When I torqued my barrel, I set my wrench to 33 ft/lb.  To line up the barrel nut with the gas tube hole, I increased the torque wrench 1 ft/lb at a time until I had proper allignment.  The final torque was 36 ft/lb.  Also, it really does help to re-torque 2 more times.  That is after the first torque up, loosen the barrel nut, and torque again.  Then repeat one more time.

Well, it looks like the Torque Weenies have done all the damage they can over in Troubleshooting and have now decided to invade Build It Yourself and poison the minds of new AR builders with dire warnings of torque numbers, multiple tightenings, and magic greases!!  Everyone take heed and protect yourself against this fungus-like infection!!!  Throw away your torque wrench and use a breaker bar!!!!!  Watch the barrel nut, not the wrench!!!  Live and be free!!!!!




[:P]


[Edited to ficks speling misteaks]