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Posted: 9/1/2012 9:43:52 AM EST
Screwed on the barrel nut and got it hand tight.
A quick check of alignment to see how much further I need to go for gas tube alignment and its just almost already aligned.
It took minimal (very minimal) pressure with the wrench to get the hole for the gas tube to align properly.

There is no way the barrel nut could be tighten to the next whole would doing damage to the threads or receiver.

It really can't come undone since the gas tube runs through the hole.
Is there any concern with it being on there without significant torque?
I can't think of anything to say. Nada, zip, nothing.
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Posted: 9/1/2012 10:57:10 AM EST
Everything I have read says 30lbs minimum. You will need to torque the nut down at least 3 times then align it to get the gas tube through. I assume you have grease on the threads when you hand tightened it? It should start to seat on about the 3rd tightening. That may put the notch further out.

On average mine align at about 40-55lbs. I had one that was close to 70lbs.
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Posted: 9/1/2012 12:10:29 PM EST
Originally Posted By balloo93:
Everything I have read says 30lbs minimum. You will need to torque the nut down at least 3 times then align it to get the gas tube through. I assume you have grease on the threads when you hand tightened it? It should start to seat on about the 3rd tightening. That may put the notch further out.

On average mine align at about 40-55lbs. I had one that was close to 70lbs.


So you are saying mine is definitely too loose?
It is common to go past 1 full hole to get to properly tight?
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Posted: 9/1/2012 12:30:50 PM EST
[Last Edit: 9/1/2012 12:34:25 PM EST by Gamma762]
Originally Posted By JThompson:
It is common to go past 1 full hole to get to properly tight?

Do you have the moly grease on there, or some kind of grease at least? Without the grease the movement-to-torque relationship will not be right.
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Posted: 9/1/2012 2:41:56 PM EST
Originally Posted By JThompson:
Originally Posted By balloo93:
Everything I have read says 30lbs minimum. You will need to torque the nut down at least 3 times then align it to get the gas tube through. I assume you have grease on the threads when you hand tightened it? It should start to seat on about the 3rd tightening. That may put the notch further out.

On average mine align at about 40-55lbs. I had one that was close to 70lbs.


So you are saying mine is definitely too loose?
It is common to go past 1 full hole to get to properly tight?

Understand the proper procedure.
Get a torque wrench.
Report back.



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Posted: 9/1/2012 3:20:49 PM EST
Originally Posted By Direct-Drive:
Originally Posted By JThompson:
Originally Posted By balloo93:
Everything I have read says 30lbs minimum. You will need to torque the nut down at least 3 times then align it to get the gas tube through. I assume you have grease on the threads when you hand tightened it? It should start to seat on about the 3rd tightening. That may put the notch further out.

On average mine align at about 40-55lbs. I had one that was close to 70lbs.


So you are saying mine is definitely too loose?
It is common to go past 1 full hole to get to properly tight?

Understand the proper procedure.
Get a torque wrench.
Report back.



It has to be a measured minimum of 30lbs. If it aligns with that then you should be good to go. I always set my torque wrench at 35lbs. If you feel like you are going to bust the receiver you can get a new barrel nut and try it again. Make sure you are using the proper tools for the job (ie Clam Shell upper receiver or upper receiver block, torque wrench, and vise).

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Posted: 9/1/2012 3:32:01 PM EST
If you have only hand tightened it as you describe, I am willing to bet you can feel the barrel wiggle around on the receiver if you grasp it firmly and move it around.
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Posted: 9/1/2012 4:23:46 PM EST
The barrel can definitely move around if it's not tight enough. I had a friend who asked me why his front sight was canted one day at the range. I quickly deduced the whole barrel was twisting back and forth! It would move a good quarter of an inch off center and yet still function. I never looked at the end of the gas tube inside the receiver but it was probably jacked up. Not to mention what was going on with the pin in the top of the barrel that aligns with the notch in the receiver! He sent it back to the maker and apparently this was not an uncommon problem with barrels that were completely MELONITE coated... Inside and out.

I would like to have taken it apart to see what was going on but it was a relatively new rifle and was completely taken care of by the manufacturer. He got a whole new upper. Even though he had run at least 1000 rounds thru it.
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Posted: 9/1/2012 7:21:04 PM EST
[Last Edit: 9/2/2012 8:32:37 AM EST by PFC]
A hand tight barrel nut is not acceptable.
A loose barrel is a deadline item.
Did you try to take it to the next notch to see if it would line up before reaching 80ft/lbs?
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Posted: 9/1/2012 7:43:18 PM EST
[Last Edit: 9/1/2012 7:44:27 PM EST by TrooperKbC]
Originally Posted By oneshot_onekill:
The barrel can definitely move around if it's not tight enough. I had a friend who asked me why his front sight was canted one day at the range. I quickly deduced the whole barrel was twisting back and forth! It would move a good quarter of an inch off center and yet still function. I never looked at the end of the gas tube inside the receiver but it was probably jacked up. Not to mention what was going on with the pin in the top of the barrel that aligns with the notch in the receiver! He sent it back to the maker and apparently this was not an uncommon problem with barrels that were completely MELONITE coated... Inside and out.

I would like to have taken it apart to see what was going on but it was a relatively new rifle and was completely taken care of by the manufacturer. He got a whole new upper. Even though he had run at least 1000 rounds thru it.


This is a rediculous claim. The interior coating of the barrel has no effect on installation. If the thing is turning within the receiver there is a problem other than the coating, such as manufacturing tolerances of the receiver and/or barrel extension. There is an indexing pin and notch that prevent twisting and the barrel should not be moving around without a good bit of force with or without the barrel nut. I have a completely melonite coated barrel and I have to hammer on it to get it out of the receiver.
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Posted: 9/1/2012 8:00:35 PM EST

Originally Posted By TrooperKbC:
Originally Posted By oneshot_onekill:
The barrel can definitely move around if it's not tight enough. I had a friend who asked me why his front sight was canted one day at the range. I quickly deduced the whole barrel was twisting back and forth! It would move a good quarter of an inch off center and yet still function. I never looked at the end of the gas tube inside the receiver but it was probably jacked up. Not to mention what was going on with the pin in the top of the barrel that aligns with the notch in the receiver! He sent it back to the maker and apparently this was not an uncommon problem with barrels that were completely MELONITE coated... Inside and out.

I would like to have taken it apart to see what was going on but it was a relatively new rifle and was completely taken care of by the manufacturer. He got a whole new upper. Even though he had run at least 1000 rounds thru it.


This is a rediculous claim. The interior coating of the barrel has no effect on installation. If the thing is turning within the receiver there is a problem other than the coating, such as manufacturing tolerances of the receiver and/or barrel extension. There is an indexing pin and notch that prevent twisting and the barrel should not be moving around without a good bit of force with or without the barrel nut. I have a completely melonite coated barrel and I have to hammer on it to get it out of the receiver.

My understanding is that if you melonite the barrel and barrel extension after they have been mated it will often cause issues. They should always be melonited separately and then put the extension on the barrel.

Torque your barrel to 30 ft lb three times (with grease on the threads first). Then attempt to reach the next hole, if you reach 90 ft lb (60 ft lb on Troy TRX and MI SS 2 barrel nuts) and are not close to lining up you have a couple of options.
1.) Try a different barrel nut
2.) Cut the lug blocking installation of the gas tube - not the preferred method
3.) Use an upper receiver lapping bar to slightly cut back the front of the upper. This works well, but you don't want to remove much
4.) You can probably do the same as 3 above by using a fine sandpaper to remove a couple thousands from the front of the receiver. If I was on a really tight budget I might try this.
5.) Attempt to torque the barrel nut over and over until it finally lines up within the torque spec. This might work if its really close to lining up.

You could always just turn it until it lines up, but you may break the upper.
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Posted: 9/2/2012 12:56:10 AM EST
Originally Posted By TrooperKbC:
Originally Posted By oneshot_onekill:
The barrel can definitely move around if it's not tight enough. I had a friend who asked me why his front sight was canted one day at the range. I quickly deduced the whole barrel was twisting back and forth! It would move a good quarter of an inch off center and yet still function. I never looked at the end of the gas tube inside the receiver but it was probably jacked up. Not to mention what was going on with the pin in the top of the barrel that aligns with the notch in the receiver! He sent it back to the maker and apparently this was not an uncommon problem with barrels that were completely MELONITE coated... Inside and out.

I would like to have taken it apart to see what was going on but it was a relatively new rifle and was completely taken care of by the manufacturer. He got a whole new upper. Even though he had run at least 1000 rounds thru it.


This is a rediculous claim. The interior coating of the barrel has no effect on installation. If the thing is turning within the receiver there is a problem other than the coating, such as manufacturing tolerances of the receiver and/or barrel extension. There is an indexing pin and notch that prevent twisting and the barrel should not be moving around without a good bit of force with or without the barrel nut. I have a completely melonite coated barrel and I have to hammer on it to get it out of the receiver.


It is spelled ridiculous, and it makes perfect sense if the barrel extension comes loose from the barrel.
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Posted: 9/2/2012 6:55:40 AM EST
Originally Posted By jaqufrost:
My understanding is that if you melonite the barrel and barrel extension after they have been mated it will often cause issues. They should always be melonited separately and then put the extension on the barrel.

Torque your barrel to 30 ft lb three times (with grease on the threads first). Then attempt to reach the next hole, if you reach 90 ft lb (60 ft lb on Troy TRX and MI SS 2 barrel nuts) and are not close to lining up you have a couple of options.
1.) Try a different barrel nut
2.) Cut the lug blocking installation of the gas tube - not the preferred method
3.) Use an upper receiver lapping bar to slightly cut back the front of the upper. This works well, but you don't want to remove much
4.) You can probably do the same as 3 above by using a fine sandpaper to remove a couple thousands from the front of the receiver. If I was on a really tight budget I might try this.
5.) Attempt to torque the barrel nut over and over until it finally lines up within the torque spec. This might work if its really close to lining up.

You could always just turn it until it lines up, but you may break the upper.

1) 80 ft lbs is the top of the range and you had better have a good fixture if you choose to run up that high.
2) That would be a NO.
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