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Posted: 7/21/2016 12:42:00 PM EDT
[#1]
Put the torque wrench at a 90 degree with the barrel nut.
That will eliminate the lever factor. |
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Posted: 7/21/2016 12:44:43 PM EDT
[#2]
The standard AR barrel nut tool has already taken this torque specification into account. Just set your wrench to the recommended torque and rest easy.
Some non-standard barrel nut tools might be off one way or the other, but the torque value is so broad that it isn't a huge deal, either. Most of those types are used for proprietary barrel nuts that you don't have to line up any notches for the gas tube. I typically set my torque wrench to 40lbs and just call it good. |
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Posted: 7/21/2016 12:49:54 PM EDT
[#3]
35 to 90 lbs
Even when adding antiseize or grease this band is wide enough that you don't need to fuss over it. |
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Posted: 7/21/2016 1:14:55 PM EDT
[#4]
tanx guys
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Posted: 7/21/2016 1:45:42 PM EDT
[#5]
1. Light coat of molybdenum grease on the threads.
2. Torque to 30 ft.lb. 3. Loosen (don't use the torque wrench - they're not designed for that) 4. Repeat steps 2, 3 two more times. 5. Torque to 30 ft.lb. one more time. 6. Set wrench to 80 ft.lb. 7. Tighten until the gas tube lines up with the next slot in the nut. This should be well before you hit 80 ft.lb. |
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Posted: 7/21/2016 8:34:53 PM EDT
[#6]
Quote HistoryQuoted:
1. Light coat of molybdenum grease on the threads. 2. Torque to 30 ft.lb. 3. Loosen (don't use the torque wrench - they're not designed for that) 4. Repeat steps 2, 3 two more times. 5. Torque to 30 ft.lb. one more time. 6. Set wrench to 80 ft.lb. 7. Tighten until the gas tube lines up with the next slot in the nut. This should be well before you hit 80 ft.lb. All of this, plus the barrel nut wrench goes IN LINE WITH the torque wrench. When you do the math, the difference in torque "seen" by the nut is on the order of 3-4 foot-pounds, but THAT'S WHAT IT'S DESIGNED FOR. If you put the barrel nut wrench at a 90º angle to the torque wrench, yes, you reduce the "added torque," but the specified 30-80 foot-pounds of torque is AS APPLIED WITH THE WRENCH IN LINE. So yes, you are over analyzing it. Remember that the basic procedure was written for an overworked armorer, not a machinist or engine mechanic. The procedure CLEARLY calls for the barrel nut wrench (the "combination wrench") to be in line with the torque wrench, which means that the procedure takes the difference in "actual" and "indicated" torque into account. |
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Posted: 7/21/2016 9:13:22 PM EDT
[#7]
With the wide range of acceptable barrel nut torque I wouldn't sweat it.
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Posted: 7/22/2016 12:00:27 PM EDT
[#8]
I try to go to the lighter side of torque. The precision shooter guys say less is best. I don't know if they are correct but I've not had a problem at around 40 and the groups are good.
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Posted: 7/22/2016 8:35:57 PM EDT
[#9]
Quote HistoryQuoted:
I try to go to the lighter side of torque. The precision shooter guys say less is best. I don't know if they are correct but I've not had a problem at around 40 and the groups are good. The precision shooter guys don't use just any upper or barrel, and they have a lot of other techniques used in building a rifle that may or may not "help" with accuracy. If you use the well respected procedure of torquing the nut to 30 foot pounds at least 3 times before going for the final torque to align a gas tube notch, and keep your torque between 30 and 80 foot pounds, don't sweat if it goes toward the high side. If you aren't making progress in getting that notch to line up, back off and retorque - between distributing the grease throughout the nut's and upper's threads, and knocking down any high spots, a few extra attempts often bring the final torque down quite a bit. |
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Posted: 7/22/2016 10:27:05 PM EDT
[#10]
Quote HistoryQuoted:
1. Light coat of molybdenum grease on the threads. 2. Torque to 30 ft.lb. 3. Loosen (don't use the torque wrench - they're not designed for that) 4. Repeat steps 2, 3 two more times. 5. Torque to 30 ft.lb. one more time. 6. Set wrench to 80 ft.lb. 7. Tighten until the gas tube lines up with the next slot in the nut. This should be well before you hit 80 ft.lb. Good post. |
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Posted: 7/22/2016 10:31:53 PM EDT
[#11]
Quote HistoryQuoted:
The precision shooter guys don't use just any upper or barrel, and they have a lot of other techniques used in building a rifle that may or may not "help" with accuracy. If you use the well respected procedure of torquing the nut to 30 foot pounds at least 3 times before going for the final torque to align a gas tube notch, and keep your torque between 30 and 80 foot pounds, don't sweat if it goes toward the high side. If you aren't making progress in getting that notch to line up, back off and retorque - between distributing the grease throughout the nut's and upper's threads, and knocking down any high spots, a few extra attempts often bring the final torque down quite a bit. Quote HistoryQuoted:
Quoted:
I try to go to the lighter side of torque. The precision shooter guys say less is best. I don't know if they are correct but I've not had a problem at around 40 and the groups are good. The precision shooter guys don't use just any upper or barrel, and they have a lot of other techniques used in building a rifle that may or may not "help" with accuracy. If you use the well respected procedure of torquing the nut to 30 foot pounds at least 3 times before going for the final torque to align a gas tube notch, and keep your torque between 30 and 80 foot pounds, don't sweat if it goes toward the high side. If you aren't making progress in getting that notch to line up, back off and retorque - between distributing the grease throughout the nut's and upper's threads, and knocking down any high spots, a few extra attempts often bring the final torque down quite a bit. Another good post with good advice. I've had to go to 80 to get alignment of barrel nut indentation with gas tube opening but it works fine. I fear disassembly more at higher torque though. I don't like to get even close to the edge with forcing aluminum. |
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Posted: 7/22/2016 11:34:35 PM EDT
[#12]
I'm glad I found this thread because I just put a barrel on this evening and ran into my first problems doing so. When I tightened the nut by hand it didn't line up, of course. I then put my wrench on it and at 35 ft lbs, it just past the mark. When I tightened it up some more, I did it again and missed the mark. I tightened it up a third time, which was just over 80 ft lbs, I got it to line up. I know, way tighter than necessary. My question is, I've been told not to loosen the nut but go to the next notch. Could I have just loosened it up a bit, to get it to line up? I didn't hurt anything at that torque. Didn't strip it, bend or crack the receiver so it should be fine, correct?
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Posted: 7/23/2016 5:38:11 AM EDT
[#13]
if you go to far loosen it up again to 30ftlbs then go very slowly till it lines up. Dont keep tightening till you get it lined up. No you cant loosen it up to get it lined up. Just start over.
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Posted: 7/23/2016 7:39:15 AM EDT
[#14]
Should I just leave it alone or pull everything apart and loosen it? I have it all put together now and everything lines up correctly.
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Posted: 7/23/2016 8:21:05 AM EDT
[#15]
Quote HistoryQuoted:
Should I just leave it alone or pull everything apart and loosen it? I have it all put together now and everything lines up correctly. The world won't end if you leave the thing all put together. But I'd have loosened it all the way and taken another stab at getting the torque within the specified limits. The purpose of the amount of torque on the barrel nut is to place a known amount of clamping force on the barrel extension flange - the aluminum upper is stretched in the process and acts as a sort of "spring" to keep that clamping force applied. Going WAY over 80 foot pounds will probably only be a problem with lower quality uppers, or (perhaps) billet uppers (and that's only theoretical). But when I have a spec to meet, like "at least 30 but no more than 80," my OCD keeps me from leaving something that's outside that spec as is. |
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Posted: 7/23/2016 7:30:03 PM EDT
[#16]
May sound stupid but I wasnt aware that I could "just start over". I dont know why I didnt think of doing it. Thanks for enlightening me.
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Posted: 7/23/2016 9:20:56 PM EDT
[#17]
It never hurts to just loosen that nut all the way and start torquing again. I had one combination of upper, barrel and nut that took me EIGHT times before the barrel nut notch started to line up with a reasonable amount of torque. I'm stubborn.
Better to get it "right" than to worry about it, right? |
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Posted: 7/24/2016 12:18:14 AM EDT
[#18]
Quote HistoryQuoted:
Put the torque wrench at a 90 degree with the barrel nut. That will eliminate the lever factor. All these know it all crack me up..... This guy (2nd post) has it correct. It's a law of physics that allows this method to read correctly. Put the torque wrench at a 90deg angle to the barrel nut wrench if you want correct torque reading. For those who need a crash course in using hand tools here is a link to a torque calculator for you to see for your self...... and for those saying the wrench manufacturers take this into account, I didn't realise they had the ability to overcome the laws of physics when they built a $15 tool LMFAO.. Torque wrench calculator |
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Posted: 7/24/2016 2:10:58 AM EDT
[#19]
let's consult the manual M16 Armorer Manual page 102 or 3-31 diagram shows tq wrench inline with GI barrel wrench nothing about 90deg
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Posted: 7/24/2016 8:52:05 AM EDT
[#20]
Quote HistoryQuoted:
Put the torque wrench at a 90deg angle to the barrel nut wrench if you want correct torque reading. What do you consider the "correct" torque reading? A value that has nothing to do with the torque specified in all the technical data, or a value that is measured in accordance with the technical data? The Technical Manual calls for the combination wrench to be in line with the torque wrench here on page 3-41. There is something close to 2" between the center of the barrel wrench portion of the combination wrench and the center of the 1/2" drive. Doing the math, there is a very, very small difference between the "actual" torque applied to the nut, and the torque indicated on the wrench. This is taken into account in the TM's procedure. So the "correct" torque reading, to my way of thinking, is something between 30 and 80 foot-pounds of torque, with the combination wrench (or other adapter of similar dimensions - and I haven't seen one that wasn't really close) IN LINE with the torque wrench. While it may be cool, knowing the actual torque you're applying to the nut is irrelevant. The torque is needed to apply a solid clamping force on the barrel extension flange, and that's all. Nothing magic or quantum physics about it. And there's no reason to rethink the 50+ year old procedure and torque requirements, either. |
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Posted: 7/24/2016 12:00:41 PM EDT
[#21]
i lucked out my last (latest) build. the barrel nut was right at 35 lbs when it lined up. usually i got to go to 80-90 to get the gas tube lined up.
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Posted: 7/24/2016 5:47:23 PM EDT
[#22]
So mine being that amount, is no biggie?
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Posted: 7/24/2016 6:58:41 PM EDT
[#23]
Quote HistoryQuoted:
So mine being that amount, is no biggie? Not really. Next time, use the tricks and techniques we've given here and you'll get your barrel nut torqued smoother and easier. 
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Posted: 7/24/2016 8:20:47 PM EDT
[#24]
It doesn't have to be at 80-90 ft lbs. If everything lines up at 35 then ur good. If u try to go to 90 it may or may not line up.
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Posted: 7/25/2016 4:41:35 PM EDT
[#25]
Quote HistoryQuoted:
Not really. Next time, use the tricks and techniques we've given here and you'll get your barrel nut torqued smoother and easier. Quote HistoryQuoted:
Quoted:
So mine being that amount, is no biggie? Not really. Next time, use the tricks and techniques we've given here and you'll get your barrel nut torqued smoother and easier. I'm putting together a 9mm upper for my first upper assembly effort. Are there any additional/different steps I need to follow? I know there's no gas tube to worry about getting lined up properly, so I'm assuming it's just the torque/loosen X three and GTG. Also, will an Reaction Rod work for this, or should I use another method? |
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Posted: 7/25/2016 5:29:40 PM EDT
[#26]
A Reaction Rod will NOT work with an AR 9mm barrel - it locks into the barrel extension's lugs, and 9mm AR barrels don't have locking lugs. A $20 pair of aluminum barrel vise blocks should work just peachy with most barrels. Just use rosin or any of the other suggestions posted here (and elsewhere) to keep the barrel from turning while you torque the nut. Using the "tighten three times" (or more than 3 times) procedure really helps getting things put together without much fuss.
I try to keep even blowback uppers' barrel nuts lined up with the gas tube hole (or its location, anyway) because some rail systems lock into the barrel nut's notches. I wound up having to remove and reinstall one upper's barrel because slapping a rail on it just didn't work - the nut wasn't anywhere near aligned, and that canted the rail. A lot. |
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Posted: 7/25/2016 7:15:44 PM EDT
[#27]
Thanks. I've never looked at the chamber end of a 9mm AR barrel.
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Posted: 7/25/2016 7:30:39 PM EDT
[#28]
Quote HistoryQuoted:
1. Light coat of molybdenum grease on the threads. 2. Torque to 30 ft.lb. 3. Loosen (don't use the torque wrench - they're not designed for that) 4. Repeat steps 2, 3 two more times. 5. Torque to 30 ft.lb. one more time. 6. Set wrench to 80 ft.lb. 7. Tighten until the gas tube lines up with the next slot in the nut. This should be well before you hit 80 ft.lb. This is the way I have always done it and it usually works out around 40-45 ft lbs when the slot and gas tube line up. I have seen some nuts on at over 120 ft lbs and that is just crazy but it worked. |
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Posted: 7/26/2016 2:07:44 PM EDT
[#29]
The procedure in the Armorers Manual is the correct way to do it.
That being said; the armorers manual does not mention the actual torque applied to the nut. The 90° method is absolutely correct for the actual torque applied to the nut when using two wrenches in combination. I learned about this method many years ago when retorquing engine head bolts that were under rocker arms. It is clearly described in some engine service manuals. |
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Posted: 7/26/2016 3:21:35 PM EDT
[#30]
The whole torque wrench thing is almost laughable. The range is so broad, it basically reads: "Tighten the barrel nut". If you can't turn a wrench and stop in between 30-80 ft-lbs, you need to turn in your man card.
I will conceded that there are times when things aren't lining up right for the gas tube/barrel nut, but in my experience, this happens on rare occasions. |
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