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Posted: 7/14/2008 9:43:07 PM EDT
[Last Edit: 7/14/2008 9:43:27 PM EDT by asu174]
When I tighten my barrel nut, I have two options.

1. Lightly turn 1/2 "notch" turn from "finger tight".
2. Apply about 100 ft lbs of torque and wail on it until it gets to the next notch.

Which should I do? I'm using a wheel bearing grease on the threading.
Link Posted: 7/15/2008 2:11:58 AM EDT
Something don't sound right here.....



It does not appear to be 1/2" between the next slot on regular barrel nuts or even custom ones like this:



And I have never experience an installation where one slot is loose and the next requires 100#s of torque.......

Is your barrel nut unlike these shown above?

mike

ps - photos borrowed from the BIY tacked thread above
Link Posted: 7/15/2008 7:38:22 AM EDT
option 3. Tighten the barrel nut up, back it off, repeat until you get it where you need it (usually about 3 times).
Link Posted: 7/15/2008 7:55:11 AM EDT

Originally Posted By mr_wilson:
Something don't sound right here.....


It does not appear to be 1/2" between the next slot on regular barrel nuts or even custom ones like this:

And I have never experience an installation where one slot is loose and the next requires 100#s of torque.......

Is your barrel nut unlike these shown above?


Its like the top one minus the handguard retainter. The barrel nut butts up directly against the receiver. That's probably why there is no play.

If I go with option 3, and "loosen" it to find the slot, I'm back at the same relatively loose slot again. I have 2 holes to choose from. Not super tight and insanely tight.
Link Posted: 7/15/2008 8:18:52 AM EDT

Originally Posted By asu174:

Originally Posted By mr_wilson:
Something don't sound right here.....


It does not appear to be 1/2" between the next slot on regular barrel nuts or even custom ones like this:

And I have never experience an installation where one slot is loose and the next requires 100#s of torque.......

Is your barrel nut unlike these shown above?


Its like the top one minus the handguard retainter. The barrel nut butts up directly against the receiver. That's probably why there is no play.

If I go with option 3, and "loosen" it to find the slot, I'm back at the same relatively loose slot again. I have 2 holes to choose from. Not super tight and insanely tight.


What he means is tighten it. Loosen it, and retighten it a few times until you can get a good torque on it. This is a process of seating the threads. You should not exceed 80 ft/lbs to get the holes lined up.

I had to do the loosen and tighten thing five times on one receiver before I goth the threads seated correctly and got the barrel nut properly "timed".

Just don't try to rush it and crank so hard that you crack the receiver.
Link Posted: 7/15/2008 8:55:18 AM EDT

Originally Posted By SSN_Doc:

What he means is tighten it. Loosen it, and retighten it a few times until you can get a good torque on it. This is a process of seating the threads. You should not exceed 80 ft/lbs to get the holes lined up.

I had to do the loosen and tighten thing five times on one receiver before I goth the threads seated correctly and got the barrel nut properly "timed".

Just don't try to rush it and crank so hard that you crack the receiver.


Yes this is what I meant
Link Posted: 7/15/2008 10:01:53 AM EDT
You may want t o check to make sure the barrel nut is not all the way against the receiver, sounds like it may be at the end and can not tighten any more. May not be the case but a possibility.
Link Posted: 7/15/2008 1:35:49 PM EDT
So the ultimate goal is to eventually work my way to that second notch to achieve optimum tightness without having to wail on it. Got it. Thanks.
Link Posted: 7/15/2008 1:49:03 PM EDT
Link Posted: 7/16/2008 5:44:26 AM EDT
tighten then loosen three or four times. I had to so the same on mine - different barrel nut though...I have the Yankee Hill one but I ran into the same type of issue. Three times was the charm for me.
Link Posted: 7/16/2008 9:13:20 AM EDT
You said, "The barrel nut butts up directly against the receiver. That's probably why there is no play." If that's the case, two options, shim between the barrel flange and barrel nut or reduce the length of the nut on the receiver side. Do you have access to other receivers and barrel nuts to compare? I'm thinking something is out of spec.
Link Posted: 7/16/2008 10:36:59 AM EDT
I had the same problem putting on my Larue FF tube nut. One hole was MAYBE 30lbs and the next was OVER 80lb, probably 100lbs with the way it felt. I am going to disassemble. apply more grease and try to "seat" the threads by working it in a couple times like mentioned above. I don't like having the nut just beyond hand tight. It shot fine though...probably not for long however.
Link Posted: 7/18/2008 3:57:04 PM EDT

Originally Posted By hdbiker1:
You said, "The barrel nut butts up directly against the receiver. That's probably why there is no play." If that's the case, two options, shim between the barrel flange and barrel nut or reduce the length of the nut on the receiver side. Do you have access to other receivers and barrel nuts to compare? I'm thinking something is out of spec.


I just meant that there is no handguard retainer between the nut and receiver. It screw right on.
Link Posted: 7/19/2008 5:29:51 PM EDT
Link Posted: 7/19/2008 10:59:09 PM EDT
Yesterday I was putting a new barrel on my AR using the DPMS multi-tool and the two pins that index the barrel nut snapped clean off at 40 foot lbs!!! Whats worse is that was the only tool I had, and no where in my town has AR tools. So....I ended up missing my local gun range's 300yd range day, that only comes once a month if that.
Link Posted: 7/20/2008 4:35:01 AM EDT
I have snapped one of the pins on one of my armorers wrench. I just drilled through the wrench and soldered in a punch (same size as missing pin and cut off handle w/ dremel) as a ghetto replacement. Should work for you until you can get a replacement tool
Link Posted: 7/20/2008 11:26:55 AM EDT
[Last Edit: 7/20/2008 11:29:48 AM EDT by hk45shooter]
Ooops.
Link Posted: 7/20/2008 11:28:12 AM EDT

Originally Posted By QUIB:
The trick is:

- Plenty of grease on the receiver threads and barrel nut threads.
- Tighten, back off, then repeat until you reach the correct alignment.

The military -23 states to repeat the tighten/loosen sequence three times. Sometimes it can take more than three times. But never back off the barrel nut to achieve alignment.


QUIB,
I have never understood this quote, do you tighten it up then back the barrel nut off a couple of threads, or do you back the barrel nut all the way off the receiver threads each time?

Thanks
Link Posted: 7/20/2008 11:47:52 AM EDT
[Last Edit: 7/20/2008 11:49:13 AM EDT by Gamma762]
100 ft/lbs of torque with grease is going to have a lot of potential for damage to the receiver.

Your description of the difference between hand tight and 100 ft/lbs is nothing like any AR I've barreled either.
Link Posted: 7/20/2008 11:54:13 AM EDT
[Last Edit: 7/20/2008 11:56:06 AM EDT by innocent_bystander]

Originally Posted By asu174:
When I tighten my barrel nut, I have two options.

1. Lightly turn 1/2 "notch" turn from "finger tight".
2. Apply about 100 ft lbs of torque and wail on it until it gets to the next notch.

Which should I do? I'm using a wheel bearing grease on the threading.


I do it a little differently.

1. Set torque wrench to 30 foot pounds and tighten and release the nut 3 times. Threads have graphite free moly grease on them.

2. Bring the nut back up to 30 foot pounds.

3. Set torque wrench to the do not exceed level of 80 foot pounds. Move nut to next alignment notch after the 30 foot pound point. If the wrench clicks at the 80 foot pound setting before alignment then I back off the torque and bring it up a couple of more times until I get alignment under 80 foot pounds.
Link Posted: 7/20/2008 12:28:04 PM EDT
Link Posted: 7/20/2008 1:16:27 PM EDT

Originally Posted By QUIB:

Originally Posted By hk45shooter:
QUIB,
I have never understood this quote, do you tighten it up then back the barrel nut off a couple of threads, or do you back the barrel nut all the way off the receiver threads each time?

Thanks


Tighten, then back off. You just want to loosen the barrel nut some, not completely remove it.


Thank you.
Link Posted: 7/20/2008 1:19:54 PM EDT
Link Posted: 7/20/2008 2:57:59 PM EDT
I did a rifle today and due to using custom barrels and dpms barrel nut, physically, it would never reach the point I needed to align the gas tube. Using a micrometer, I figured out that it was physically impossible to go any further without damage to the threads or receiver. I ended up having to dremel less than a thousandth off of the barrel itself as I could not get into the nut and dremel correctly the area that needed to be removed. Essentially, the barrel collar was too thick.

Check all of the areas and look at the threads. Cranking too hard is bad and can cause some serious damage.
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