Tightening barrel nut

[FaRKle!]

EXACTLY or you have the same issue I did with my recent install. Even Noveske on the NSR Rail, states to use a grease on the barrel nut threads and you may need to tighten loosen.Thier brand specific Torque specs are 40-80 lbs. Mine was done at like 35 and after 100 rnds of frustration it came loose. Redone to 80 and wnd Ill be at the range this weekend. I'll post thr results on my other thread as not to thread jack ^-^

My NSR installs have been on the high side of the torque range as well.

[Robocop1051]

My NSR installs have been on the high side of the torque range as well.

Not just the high side. If I remember correctly, we maxed that rail at like 80 or 85.

[FaRKle!]

Not just the high side. If I remember correctly, we maxed that rail at like 80 or 85.

Yup, and later when I sold that rail to Ryan it came out to 75-80 on his too.

[Gray05]

I got a more detailed response from SI.

"Sometimes it is impossible to hit the required minimum torque

specification of 35lbs-ft and still have the gas tube hole line up with

the clearance in the nut.

Anti-seize is an alternative, however, it acts as a lubricant and the

amount of torque required dry, differs from amount needed for "wet"

applications. Usually you will need more torque under "lubricated"

conditions."

[shibiwan]

Might I suggest a barrel nut shim?

[Gray05]

Might I suggest a barrel nut shim?

I didn't know that existed but I would think that would do fine for the contingency they are describing.

Now that I understand when they would use loctite, I'm definitely going with a grease or anti-seize. I don't even know if my barrel but will be the type that has the gas tube run through it or not. If alignment issues did occur I guess loctite or a shim would take care of it.

[shibiwan]

Here's an example of a set for an AR15. I'm sure there are 308AR ones available.

 

[Zebra644]

Yep it's called a trip to  Home Depot / Lowes 

[98Z5V]

^^^ Those Spikes barrel nut shims came with the Big A$s Rail when it first came out - don't know if they still do or not, but I'd be that they do still include that. 

 

You clocked your barrel nut and checked it's gas tube position without a shim - the hole had to line up about 45-degrees out from top dead center, before tightening.  If I remember that right...  Anyways, if it didn't, you added a shim, until you got it right.  Once you had it right, at the "pre-tighten" spot, you applied torque and lined it up - perfect torque every time.

 

I still have some of those shims left over for a 5.56 gun, and I've thought about using them on builds after that...  but I just torqued those on and went with it.  The shims are good stuff, though.  You could have a rifle with high torque on the nut, shim it, and still line up perfectly at lower torque.  <thumbsup>

Edited March 11, 2014 by 98Z5V

[shibiwan]

I'm starting to think a replaceable crush washer (aluminum or copper) would probably be better. It would start to deform at the correct torque and still give some allowance in the "crush" to allow the barrel nut to align.

[FaRKle!]

I'm starting to think a replaceable crush washer (aluminum or copper) would probably be better. It would start to deform at the correct torque and still give some allowance in the "crush" to allow the barrel nut to align.

 

I don't know about that... Crush washers don't crush very evenly.

[gnatshooter]

Seems to my inexpert opinion that a crush washer designed to crush, such as washers made from crushable aluminum and copper, will continue to crush after torquing when they're being slammed by shooting. Leading you to replace the crushing washers.

 

The farm boy in me says, steel washers, no crush, tight fit, tighten to spec and be careful of anything that's a casting.

[washguy]

hmmmm.....the barrel nut has been on the ar since like forever...why try to reinvent the wheel?

its just cant be that hard to tighten down the barrel nut at a value from 40 to 80 pounds.

A simple bubba fix is if you just cant get the nut to the next notch and have the torque value that you are comfortable with is to put down a piece of wet/dry sandpaper on a flat surface and put the nut on it and sand a thou or so off the nut...it will then get you to

where it needs to be....easy peasy :) Wash

[98Z5V]

hmmmm.....the barrel nut has been on the ar since like forever...why try to reinvent the wheel?

its just cant be that hard to tighten down the barrel nut at a value from 40 to 80 pounds.

A simple bubba fix is if you just cant get the nut to the next notch and have the torque value that you are comfortable with is to put down a piece of wet/dry sandpaper on a flat surface and put the nut on it and sand a thou or so off the nut...it will then get you to

where it needs to be....easy peasy :) Wash

Can't do that - the interference surface is on the inside.  The lip on the barrel nut that mates up against the flange on the barrel.  No sanding possible for that one. 

 

If it will not go, the answer is the indexing shims.  Crush washers do crush, but they're not gonna stand up to the heat that the chamber creates.  That's why you don't use a crush washer on a muzzle device that a suppressor attaches to.

[Toolndie7]

We could just all mix and match our nuts until everybody is happy :banana:

[shibiwan]

We could just all mix and match our nuts until everybody is happy :banana:

 

^^  <lmao>  <laughs>

[washguy]

^^  <lmao>  <laughs>

mine couldnt stand the 80 lbs of torque!   <laughs>    Wash

[unforgiven]

My ex tried it,it wasn't that bad.

[washguy]

My ex tried it,it wasn't that bad.

My ex still has mine !  :puke:     Wash

Edited March 11, 2014 by washguy

[Zebra644]

I have to get mine out of he safe 

[cantshootafish]

The shims are awesome to keep your torque down to a level that does not break the upper.  Just be sure to grease them first so that the barrel nut can slide over them as it rotates.