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TSL
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Posted: 8/24/2011 6:31:13 PM

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InI in order to install a new hand guard, I had to take my AR down to the bones, and need to install a new barrel nut. Isn't is funny how one seemingly small project leads to a major project.
I got the old nut off okay, with the help of a blowtorch to heat things up, it came off quite nicely,

The question is:
What sort of thread lock, anti-seize goes on the threads of the barrel nut to the receiver?

I am thinking of high heat automotive anti-seize, by maybe Locktite Red ??

How tight to torque the barrel nut to?

I am thinking just enough to route the gas rod through.


This is my first barrel / receiver disassembly - any tips would be appreciated.

TSL

a308garand
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Posted: 8/24/2011 7:08:27 PM
[Last Edit: 8/24/2011 7:12:00 PM by a308garand]
Use a bit of grease or regular anti-seize on the barrel nut. NO loctite!

Install the barrel and torque the nut to 30 pounds minimum. To get the gas tube hole aligned, keep tightening nut to get to the sweet spot (The nut ring and gas tube hole in alignment). Don't torque over 80 pounds to get the hole aligned.

"Barrel Nut - 30 Ft. lbs. Minimum, not to exceed 80 Ft. Lbs. to align the next slot in the barrel nut."

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Herknav90
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Posted: 8/24/2011 8:38:37 PM
[Last Edit: 8/24/2011 9:10:14 PM by Herknav90]
Originally Posted By TSL:
InI in order to install a new hand guard, I had to take my AR down to the bones, and need to install a new barrel nut. Isn't is funny how one seemingly small project leads to a major project.
I got the old nut off okay, with the help of a blowtorch to heat things up, it came off quite nicely,

The question is:
What sort of thread lock, anti-seize goes on the threads of the barrel nut to the receiver?

I am thinking of high heat automotive anti-seize, by maybe Locktite Red ??

How tight to torque the barrel nut to?

I am thinking just enough to route the gas rod through.


This is my first barrel / receiver disassembly - any tips would be appreciated.

TSL



Really? A blow torch? WOW! I just use a wrench and the upper vise clamp. ETA: I think I remember someone saying a few MFGs use locktite on their barrel nuts...You may have had one like this...Apologies!

Grease...Moly Grease...I actually found the white paste at a boat shop. They use it to lube and keep corosion off boat props.

Loctite Red? Please don't. The gas tube locks this thing in place. 30 ft lbs is more than enough. I usually end up dialing up 40 ft lbs to gett the next slot for the gas tube...I rarely get to the click.


The specs I believe are as advertised 30-80 ft lbs. It has been noted by builders that the least amount of torque makes the rifle more accurate. I guess I can follow that, but I still like the min setting.
fivonut
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Posted: 8/24/2011 11:30:50 PM
I just did one today. It was a DPMS barrel nut and their instructions said to torque to 35ftlbs then tighten to the next hole not going over 85ftlbs. They way I did it was to torque the barrel nut to 35ft lbs. Then I set my Torque wrench for 80 ft. lbs. and tightened the nut until the gas tube lined up. I was hoping that it would align before the wrench clicked. Unfortunately, it clicked just as the hole came into alignment. Would I be better off to back it off to previous hole. I'm guessing that would put me in the 25-30 ft lb range.
a308garand
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Posted: 8/25/2011 12:43:48 AM
[Last Edit: 8/25/2011 12:45:49 AM by a308garand]
Torque the nut to 30 pounds, then loosen it. Repeat a total of three times, tight-loose-tight, to get the threads to set. Next, try to torque to the alignment without going over 80 pounds. You will find it now aligns to the sweet spot sooner.

You want it to align while going tight. Backing it off, loosen, will make it loose.
"Your times is over! You are gonna die bloody; all you can do is pick where!"
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TSL
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Posted: 8/25/2011 8:28:54 AM
Guys - thanks for the tips, its really appreciated. This rifle is a Rock River. There is a nut that screws onto the barrel nut that backs onto the handguard. This has some sort of thread locker in it. Also, the barrel nut to the receiver had a thread locker on it.

I had to put a butane soldering torch to them and warm em up to get it off. The parts just barely started smoking when they could turn easily.

Also, there was no crush washer, no split ring in the barrel nut assembly. This was simply, receiver - barrel - barrel nut.

Thanks for your insights and tips.

I am going to use a bit of high heat automotive anti-seize on the barrel nut threads.

TSL
TSL
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Posted: 8/27/2011 12:23:45 PM
Next problem - lockup issues:

The meplat (tip of bullet) catches on the leading edge of the magwell right below or at the feed ramps.

And once a round is chambered, the bolt has a real hard time unlocking. I have to slam it on the buttstock sometimes while pulling the cocking handle.

Its very difficult to get a round to unchamber.

any thoughts?
LMTRocks
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Posted: 8/27/2011 1:20:19 PM
The barrel nut for the new Daniel Defense MFR specifies 50ft-lbs to it, so not all barrel nuts are created equal. USGI range is 30-80, and the Troy TRX is 30-60.
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chasw
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Posted: 8/27/2011 1:30:35 PM
tsl: I too recently upgraded to a FF handguard, the YHM customizable model. After applying moly grease to protect the threads, I started tightening the YHM barrel nut. A standard AR-15 wrench will do the job. I don't have a torque wrench. I found the aluminum nut from Yankee Hill needed more "jiggling" than the original milspec nut from Colt. It really pays to keep working the nut back and forth, testing its "30 fl-lb limit" until its fully seated and torqued to the next gas tube hole.

One trick that proved useful for me was - when I thought it was finished, I grabbed the end of the barrel and wiggled it. With the upper receiver firmly fixed in your vise, there should be no looseness at all. Should be rock solid. As it turned out, my barrel did wiggle and I spent more time back and forth with the wrench to get the YHM nut all the way down. I got the feeling tiny little pieces of aluminum were being ground off of tiny burrs inside the aluminum threads. In an extreme case, after tightening and loosening the nut for a while, one could remove it entirely, clean out the shavings including those on the upper's threads, reapply moly grease and screw the nut back on again. - CW
a308garand
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Posted: 8/27/2011 3:26:17 PM
Originally Posted By TSL:
Next problem - lockup issues:

The meplat (tip of bullet) catches on the leading edge of the magwell right below or at the feed ramps.
Tighten the magazine catch one turn and or try a different magazine. If its sitting slightly too low at the front end of the magazine, maybe the magazine catch is in need of replacement with better quality part.

And once a round is chambered, the bolt has a real hard time unlocking. I have to slam it on the buttstock sometimes while pulling the cocking handle.

Its very difficult to get a round to unchamber.

Lube up the rifle and shoot 100 rounds to break in the parts. The edges and such will marry to eachother and begin to be fitted. It should smooth out very quickly.

any thoughts?


"Your times is over! You are gonna die bloody; all you can do is pick where!"
~Sheriff to Butch and Sundance