AR Barrel Nut Torque - Nut won't line up...

[outrider58]

Just wondering. What was the minimum torque when the gas hole did line up?

 

[topgun]

Try making use of Geissele reaction rod( from a gunsmith maybe) and/or try a different torque wrench. I thought mine was good to go(craftsman) turned out it was out of specs.

 

[sailskidrive]

Why not just buy a new upper receiver? You spent a premium on that Noveske barrel, might as well match it up with one that is in spec.

 

[BenL]

Just wondering. What was the minimum torque when the gas hole did line up?

~20lbs, or so. At the minimum of 30, no good. At 80, no good. It looks like a 1/1000" shim would do the trick.

 

[BenL]

Why not just buy a new upper receiver? You spent a premium on that Noveske barrel, might as well match it up with one that is in spec.

I guess I could buy a new upper receiver, but if a shim is an acceptable alternative, I'll try that.

 

[BenL]

Okay, understand... when the nut is properly indexed for the rail is there a tooth on the standard barrel nut that interferes with the gas tube?

When the gas tube is aligned, so are the rail nubs.

 

[E.Shell]

....I'm using Mobil 1 Synthetic Grease on the threads....

Wait...What?

Does it squeak/chirp and stop cold when it gets tight? Synthetic lubricants work well for certain things, but this situation is a little unusual.

Due to the close contact between dissimilar metals (aluminum receiver to steel barrel nut). the recommended lubricant is molybdenum dysulfide grease. Moly prevents galling between the unlike metals upon installation and reduces the chances of electrolysis causing corrosion and freezing these parts together.

R.T.F......er...I mean "Please see page 3-39 and 3-40 of the armorer's manual:" http://www.ar15.com/content/webPDF/TM9-1005-319-23.pdf

Further, moly grease will impact into the metal's surface and enhance lubricity. IMO, thoroughly clean the barrel nut and upper receiver threads to remove the incorrect lubricant and work some moly grease into the threads, then follow the 'torque/loosen/torque/loosen..." procedure and you can probably get it to index correctly.

 

[303_enfield]

I use this if the barrel nut won't line up after three torques an one try.
http://www.midwayusa.com/product/82...eiver-lapping-tool-ar-15?cm_vc=ProductFinding

Use moly as E.Shell stated. As for buying another upper. The upper is the "cheap" part. Well, with good barrels running $600+. Also, read up on bedding the barrel. It's easy

Another tool type:
http://www.midwayusa.com/product/810457/ptg-upper-receiver-lapping-tool-ar-15?cm_vc=ProductFinding

 

[outrider58]

I use this if the barrel nut won't line up after three torques an one try.
http://www.midwayusa.com/product/82...eiver-lapping-tool-ar-15?cm_vc=ProductFinding

Use moly as E.Shell stated. As for buying another upper. The upper is the "cheap" part. Well, with good barrels running $600+. Also, read up on bedding the barrel. It's easy

Another tool type:
http://www.midwayusa.com/product/810457/ptg-upper-receiver-lapping-tool-ar-15?cm_vc=ProductFinding

Just ordered one.

 

[lennyk]

Great thread...short of gas block installation, this is the most important part of an AR build. Makes me more of a fan of the "no index" required barrel nuts. (Daniel Defense, Geissele, etc).

 

[outrider58]

Great thread...short of gas block installation, this is the most important part of an AR build. Makes me more of a fan of the "no index" required barrel nuts. (Daniel Defense, Geissele, etc).

My D.Defence requires indexing.

 

[BenL]

Wait...What?

Does it squeak/chirp and stop cold when it gets tight? Synthetic lubricants work well for certain things, but this situation is a little unusual.

Due to the close contact between dissimilar metals (aluminum receiver to steel barrel nut). the recommended lubricant is molybdenum dysulfide grease. Moly prevents galling between the unlike metals upon installation and reduces the chances of electrolysis causing corrosion and freezing these parts together.

R.T.F......er...I mean "Please see page 3-39 and 3-40 of the armorer's manual:" http://www.ar15.com/content/webPDF/TM9-1005-319-23.pdf

Further, moly grease will impact into the metal's surface and enhance lubricity. IMO, thoroughly clean the barrel nut and upper receiver threads to remove the incorrect lubricant and work some moly grease into the threads, then follow the 'torque/loosen/torque/loosen..." procedure and you can probably get it to index correctly.

Winner! Did the above and it lined up. It's still 80 lbs, but at least it's lined up. Thanks, Ed.

 

[TripleEight]

You probably already know this, but if you're barrel nut wrench is extended off of your torque wrench, the actual torque will be higher than the reading on the torque wrench.

 

[BenL]

You probably already know this, but if you're barrel nut wrench is extended off of your torque wrench, the actual torque will be higher than the reading on the torque wrench.

For me, I use a long torque wrench (24"?) and a short adapter (~1", maybe?), so my "L" was long and "A" was very short. The difference is inconsequential. It's not the space shuttle, it's a barrel nut.

 

[lennyk]

Wait...What?

Does it squeak/chirp and stop cold when it gets tight? Synthetic lubricants work well for certain things, but this situation is a little unusual.

Due to the close contact between dissimilar metals (aluminum receiver to steel barrel nut). the recommended lubricant is molybdenum dysulfide grease. Moly prevents galling between the unlike metals upon installation and reduces the chances of electrolysis causing corrosion and freezing these parts together.

R.T.F......er...I mean "Please see page 3-39 and 3-40 of the armorer's manual:" http://www.ar15.com/content/webPDF/TM9-1005-319-23.pdf

Further, moly grease will impact into the metal's surface and enhance lubricity. IMO, thoroughly clean the barrel nut and upper receiver threads to remove the incorrect lubricant and work some moly grease into the threads, then follow the 'torque/loosen/torque/loosen..." procedure and you can probably get it to index correctly.

You are technically correct on the proper, Mil-Spec call out for a Government contract. However, the issue is not the grease specifically but rather the graphite content. Mobil 1 Synthetic has no graphite (it is synthetic). Graphite is a conductor and aluminum is usually a less noble (anode) compared to other metals. But also, unless you are a Navy Seal and immersing your rifle in salt water or are running a current through it, or if the rifle is constantly outdoors, I doubt galvanic corrosion would ever become an issue.