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9/19/2017 7:27:10 PM
Posted: 12/22/2005 12:27:19 PM EDT
I'm talking about the big nut that you attach the barrel to the upper receiver?
Link Posted: 12/22/2005 12:43:17 PM EDT
Umm you realize you can download the -23&P free from this site. It has all that information in it in chapter 3?

But to answer your question Minimum of 30ft-lbs, but NEVER more than 80 ft lbs (you start bending teeth at 90 - ask me how I know...)

It's covered on pages 3-41 through 3-42 of the -23&P
Link Posted: 12/22/2005 1:38:24 PM EDT
I think it is a 1/4 turn before it breaks
Link Posted: 12/22/2005 8:43:53 PM EDT
There is no "proper torque" where the barrel nut will line up to allow the gas tube to be installed.

There is only a range... as said above, 30-80 ft-lb. Nothing magic about it, you just need it tight enough to not loosen by itself (30 ft lb) and then proceed on up to align the next notch. If it lines up at 30, you are good to go. Hell, if it lined up at 25, I'd leave it alone and stick in the gas tube.
Link Posted: 12/23/2005 4:48:16 AM EDT
[Last Edit: 12/23/2005 5:06:23 AM EDT by TacticalStrat]

Originally Posted By A_Free_Man:
There is no "proper torque" where the barrel nut will line up to allow the gas tube to be installed.

There is only a range... as said above, 30-80 ft-lb. Nothing magic about it, you just need it tight enough to not loosen by itself (30 ft lb) and then proceed on up to align the next notch. If it lines up at 30, you are good to go. Hell, if it lined up at 25, I'd leave it alone and stick in the gas tube.




The problem I experienced was that it lined up at 25 lbs and it required about 80 lbs to get it to line up on the next slot. 25 lbs did not feel tight enough at all so I took it to 80 lbs. Using grease on the threads is critical when going to around 80 lbs torque.
Link Posted: 12/23/2005 11:26:15 AM EDT

Originally Posted By TacticalStrat:
The problem I experienced was that it lined up at 25 lbs and it required about 80 lbs to get it to line up on the next slot. 25 lbs did not feel tight enough at all so I took it to 80 lbs. Using grease on the threads is critical when going to around 80 lbs torque.



Loosen and retighten it a few times, and the torque values will diminish somewhat.
Link Posted: 12/23/2005 1:23:28 PM EDT
Link Posted: 12/23/2005 1:39:58 PM EDT

Originally Posted By Tweak:
man you guys are good

Nobody's mentioned moly grease yet... It makes a difference, both when you install the barrel to start with and when you decide you're going to change it (or put a rail system on it) later.

When I built my 20" I test fitted the barrel nut to make sure I could actually get it to line up and turn properly, and it was HARD to turn. The phosphate on the upper seemed to be particularly rough, though the threads were very clean. When I put the grease on the threads it made all the difference in the world! By the way, I used aerospace-quality molybdenum disulfide grease (excess from a brake job on an RF-4C; NO KIDDING!), not automotive grease.
Link Posted: 12/23/2005 1:46:44 PM EDT
[Last Edit: 12/23/2005 5:33:53 PM EDT by Forest]

Originally Posted By GHPorter:
Nobody's mentioned moly grease yet...


Yes they have, read a few posts up.
Link Posted: 12/23/2005 2:34:52 PM EDT
[Last Edit: 12/23/2005 2:39:36 PM EDT by TacticalStrat]

Originally Posted By GHPorter:

Originally Posted By Tweak:
man you guys are good

Nobody's mentioned moly grease yet... It makes a difference, both when you install the barrel to start with and when you decide you're going to change it (or put a rail system on it) later.

When I built my 20" I test fitted the barrel nut to make sure I could actually get it to line up and turn properly, and it was HARD to turn. The phosphate on the upper seemed to be particularly rough, though the threads were very clean. When I put the grease on the threads it made all the difference in the world! By the way, I used aerospace-quality molybdenum disulfide grease (excess from a brake job on an RF-4C; NO KIDDING!), not automotive grease.


.

I mentioned it in my post above. I had the same experience as you. I cleaned the threads and tried to torque the nut to get the slot lined up. Once I reached around 65 ft lbs, the nut did not want to move anymore. I had some lithium bearing grease handy, so I loosened the nut and applied lithium grease to the threads. It then torque smooth as silk to about 80 ft lbs where the slot lined up. I don't think you need any special kind of grease to torque the nut. I'm sure any high temp lithium bearing grease ( a few bucks at any auto-parts store) will do the job and stay there providing many years of protection against seizing (if you ever need to remove it again).
Link Posted: 12/23/2005 4:12:09 PM EDT
[Last Edit: 12/23/2005 4:13:28 PM EDT by TonyRumore]
It sucks if you end up with a receiver and barrel nut that match up as a "betweener", ie not quite tight enough on the first slot, but so tight that shit gets fucked up if you go to the next slot. I just grab another nut or receiver at that point and try again.

If you only have one set, and you're running a standard barrel nut, I would just grind out a tooth on the nut and have the damn thing torqued like it should be. With a free float tube, you can't do that though.

Link Posted: 12/23/2005 4:29:42 PM EDT
A while back someone posted a link to someone who sells shims to go between the nut and receiver incase going to the next slot is going to be way too much. I don't have the link anymore and I have not experience with the shims but it's another alternative. I did the approach suggested above of tightening and then loosening a few times till I got the next slot in line.

GL.
Link Posted: 12/23/2005 4:43:36 PM EDT
What's the trick if you can't get it off? I tried today and broke a few teeth off. I have the regular barrel wrench with the 3 posts on it. Does the bigger barrel wrench have more posts to engage the teeth?
Thanks
Link Posted: 12/23/2005 4:54:52 PM EDT

Originally Posted By hollowhandle:
Does the bigger barrel wrench have more posts to engage the teeth?



The better armorer's wrenches have 3 posts on one side, while the other side matches the notches on a barrel nut about 3/4 of the circumference for more gripping surface.
Link Posted: 12/23/2005 5:34:36 PM EDT

Originally Posted By hollowhandle:
What's the trick if you can't get it off? I tried today and broke a few teeth off. I have the regular barrel wrench with the 3 posts on it. Does the bigger barrel wrench have more posts to engage the teeth?
Thanks


Sounds like whoever installed it didn't use grease as specified....
Link Posted: 12/23/2005 6:22:37 PM EDT

Originally Posted By TacticalStrat:
I mentioned it in my post above. I had the same experience as you. ... I'm sure any high temp lithium bearing grease ( a few bucks at any auto-parts store) will do the job and stay there providing many years of protection against seizing (if you ever need to remove it again).

Sorry, I didn't see that right away; I was looking at the troubles the original poster had and not all of the suggestions.

I'm not knocking the use of any other grease, by the way. It's essential to put some kind of grease on the threads to get things properly assembled, and unless you're the kind of stickler for detail I am, it probably doesn't matter too much which type you use. I mentioned the automotive moly stuff because there are some grades that are apparently not good to use with aluminum. Since I was going for as close to factory as possible, I dug until I managed to find the "right" stuff.
Link Posted: 12/24/2005 1:07:12 PM EDT
Link Posted: 12/24/2005 1:19:30 PM EDT

Originally Posted By Hayseed_40:
I think it is a 1/4 turn before it breaks



or a 1/4 turn past stripped.....
Link Posted: 12/26/2005 4:53:53 PM EDT
so how do I now much torgue im putting on it without a torque wrench? do i need to use one?
Link Posted: 12/26/2005 5:12:46 PM EDT
Link Posted: 12/26/2005 5:30:02 PM EDT

Originally Posted By Tweak:
torque wrenches aren't necessary if you have good understanding of tight and not tight enough.



+1
Link Posted: 12/26/2005 5:48:07 PM EDT
[Last Edit: 12/26/2005 5:49:00 PM EDT by KA3B]

Originally Posted By Tweak:
torque wrenches aren't necessary if you have good understanding of tight and not tight enough.



Damp spaghetti noodle limp torque = Not tight enough
Tighten till your elbow is smoking, then back it off an 8th turn = Tight enough


TM 9-1005-319-10

Apply molybdenum disulfide grease to the threads before installation.

Using combination wrench (10) and torque wrench, torque barrel nut assembly (9) to 30 ft-lb (40.5 N-m).

Torque is measured when both wrenches are used together.

Three times torquing procedure provides for a better thread fit and prevents barrel nuts from becoming loose.

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 gas tube.

12. Torque the barrel nut assembly again to 30 ft-lb (40.5 N-m) while maintaining sight alignment.
The barrel nut assembly may be tightened beyond 30 ft-lb (40.5 N-m) to align the barrel nut assembly serrations for proper gas tube clearance.
Never loosen the barrel nut assembly to align for gas tube clearance.
Link Posted: 12/26/2005 5:57:04 PM EDT
two grunts tight should do it
Link Posted: 12/26/2005 11:25:47 PM EDT
Link Posted: 12/27/2005 6:01:25 AM EDT
[Last Edit: 12/27/2005 6:01:44 AM EDT by Dace]
Do the tighten, lossen, tighten, lossen technique until the nut aligns, it works everytime and you really shouldnt need shims.

First time I installed a barrel nut I didnt do this and tried to align it with one turn, I stripped and broke most of the teeth on the barrel nut.



Link Posted: 12/27/2005 8:09:32 AM EDT
What brand of barrel wrench did you use? I used a DPMS did a fine job,returned to brownells and got a Smith Enterprize Wrench , I haven't tried it yet. I hate to say it but, I think you are using a cheap wrench.
Link Posted: 12/27/2005 8:57:38 AM EDT
.
Link Posted: 12/27/2005 5:56:10 PM EDT
do you use grease for the tighten/loosen trick?
Link Posted: 12/27/2005 6:31:34 PM EDT

Originally Posted By christ0ph:
do you use grease for the tighten/loosen trick?



Yes, the grease is really to keep the reaction between steel and aluminum from happening, not to help you install it. I want to call it galling but I dont think thats right. Basically when steel and aluminum are in contact with each other bad things happen to the metal.
Link Posted: 12/27/2005 7:38:28 PM EDT
I had the same problem TacticalStrat had only I was fixing a crooked KAC FF system (entire upper) I had just picked up and had to get the gas tube hole to line up just right to be able to insert the locking pins to correctly index the rail system. One hole was at 25ft lbs of torque and the next hole was over 95lbs. I know some would have left it at 25ft. lbs but I personally felt uncomfortable with that. I used the molly grease and torqued and re-torqued over a dozen times (yes with a receiver block, vise and two different quality barrel wrenches) and could not stay below that 95ft. lbs of torque. I then made my own shim....see pics. The reason I slit the shim was to get it around the barrel......I'm a basement gunsmith have
http://i12.photobucket.com/albums/a236/Mark82ndABN/Shim.jpg
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