Ar barrel nut torque specs

The Best online firearms community in Louisiana.

Member Benefits:

  • Fewer Ads!
  • Discuss all aspects of firearm ownership
  • Discuss anti-gun legislation
  • Buy, sell, and trade in the classified section
  • Chat with Local gun shops, ranges, trainers & other businesses
  • Discover free outdoor shooting areas
  • View up to date on firearm-related events
  • Share photos & video with other members
  • ...and so much more!
  • jdindadell

    Not Banned!!!
    Rating - 100%
    267   0   1
    Feb 14, 2010
    4,200
    63
    Slidell
    Ok, hope this does not descend into madness...

    Built a few ar platform guns, and I have installed a few handguards, various types, that require a propitiatory barrel nut.

    Always used the correct tools and a torque wrench, actually bought a click type wrench specifically for the gunsmith tool box.

    Back in the distant past, I read up and the "spec" was 30 lb/ft "or more", so I always took that to mean the minimum torque spec was 30 lb/ft. I have not seen a maximum listed, but I have also not looked very hard for that info. It is a steel nut on an aluminum thread, and with enough force it could be damaged.

    I have had to shim (between the front of the barrel shoulder and the back of the barrel nut shoulder) to get some of the indexing types (NSR and knock offs) lined up correctly.

    I have also disassembled "factory built" uppers that had what I would describe as finger tight barrel nuts. Basically the gas tube was keeping the nut from backing off under use.

    Just interested in everyone's thoughts on barrel nut tightness. Feel free to post any legit info or links. Any other info is good too.

    Thanks!
     

    MTx11B

    Combat Vet
    Rating - 100%
    17   0   0
    Aug 31, 2013
    287
    16
    NOLA
    35 ft/lbs minimum for barrel nut + timing for GT,

    40 ft/lbs castle nut then staked

    Use aeroshell on the above I use the 90 degree method with my wrenches due to offset and also torque/release/torque/release /final torque to ensure proper specs.

    Gaskey 50-58 inch lbs
    Preferably proper staked with the ocks

    Grip screw 60 -68 inch lbs
     

    kcinnick

    Training Ferrous Metal
    Rating - 100%
    28   0   0
    Dec 24, 2008
    4,723
    38
    Baton Rouge
    It is a pretty wide range, you can take the barrel nut up to 80lbs, but I doubt you would ever need to approach that to get everything lined up.
     

    DAVE_M

    _________
    Rating - 100%
    32   0   0
    Apr 17, 2009
    8,288
    36
    ________
    First off, we need to establish that the TDP specifies torque values for specific parts.

    USGI Steel Barrel Nut torque value is between 30-80 ft/lbs in order to properly time the barrel nut without shims after applying Aeroshell 64 (formerly 33MS).

    You should ALWAYS follow the torque specs given by the manufacturer. For example, Geissele uses an aluminum barrel nut with a proprietary tool and a 40 ft/lb torque spec.

    Some barrel nuts require shims to be used, such as the ALG Defense EMR barrel nut. This is one example I can think of where you do not need a torque wrench, but you must use their proprietary barrel nut wrench and follow their instructions on how to properly shim the nut depending on how the barrel nut is timed.

    Not only should you use a quality torque wrench, you should follow the torque specs provided, and you should also note that the torque specs are always wet specs. You must lubricate the threads to achieve proper tension. Per the TDP, Aeroshell 64 is the Mil-spec designated grease for use on the barrel nut and castle nut assembly. There are other greases that can be used, but not many people actually know what it is in the grease they are planning to use. You do not want to use anything that contains graphite and you most certainly don't want to use aluminum anti-seize.

     

    DAVE_M

    _________
    Rating - 100%
    32   0   0
    Apr 17, 2009
    8,288
    36
    ________
    35 ft/lbs minimum for barrel nut + timing for GT,

    40 ft/lbs castle nut then staked

    Use aeroshell on the above I use the 90 degree method with my wrenches due to offset and also torque/release/torque/release /final torque to ensure proper specs.

    Gaskey 50-58 inch lbs
    Preferably proper staked with the ocks

    Grip screw 60 -68 inch lbs

    TDP spec for Castle Nut torque is 38-42 ft/lbs and staked in two places.
    TDP spec for Gas Key Screw torque is 50-58 in/lbs (as you've stated) and should be staked in four places. OCKS are a good choice. Older manuals called out 35-40 in/lbs.

    It is a pretty wide range, you can take the barrel nut up to 80lbs, but I doubt you would ever need to approach that to get everything lined up.

    You should not take EVERY barrel nut up to 80 ft/lbs. 30-80 ft/lbs is the TDP spec for USGI Steel Barrel Nuts.
     

    DAVE_M

    _________
    Rating - 100%
    32   0   0
    Apr 17, 2009
    8,288
    36
    ________
    Good info, many thanks.

    Lets keep it going, feel free to post up info that is specific to other brands as well.

    Branding really only indicates an assumed level of quality one should expect to receive. The majority of AR "manufacturers" don't manufacturer any parts and only assemble rifles. That's not necessarily a bad thing, but it most certainly can be if a company in question is using low quality parts, poor assembly, and little quality control.

    Bad Parts and Bad Assembly = Bad
    Good Parts and Bad Assembly = Bad

    You can't really have bad parts with good assembly practices, because good assembly practices would catch such things.

    For example, I had the opportunity to test a Springfield Armory SAINT Edge Pistol. It retails for an eye popping $1559. Upon initial inspection, I noticed the magwell was undersized. None of the magazines we had on hand would drop free and had to be forced into the gun, even with the bolt locked to the rear. One we began test firing it, after two magazines, the handguard began to rotate due to the handguard retaining screws beginning to loosen. Thankfully, I caught one before it fell into the sand. None of the handguard screws had any threadlocker and were only hand tight. Should you expect that from a $1500 AR pistol? No, but it was the result of poor quality control. As you've stated, you tore down complete uppers that were barely finger tight. When things like that happen, good luck finding the torque spec for proprietary parts used by the manufacturer.
     

    Magdump

    Don’t troll me bro!
    Rating - 100%
    163   0   0
    Dec 31, 2013
    9,396
    113
    Hammond, Louisiana
    First time I swapped a barrel on my first Colt, 50-80 ft lbs was the recommended torque. The rule of thumb is to 50 then the next cog for the gas tube. Never loosen to position the cog. with other proprietary nuts, both aluminum and steel, I start looking for match up around 30-40 if there are no specs listed, although most every handguard will have some torque specs even if you have to go online and search. It’s the aluminum nuts that concern me for obvious reasons. I’ve invested heavily in every wrench in the book for the task, but prefer the crow’s foot type for all those elongated free float handguard nuts.
     

    jdindadell

    Not Banned!!!
    Rating - 100%
    267   0   1
    Feb 14, 2010
    4,200
    63
    Slidell
    For example, I had the opportunity to test a Springfield Armory SAINT Edge Pistol. It retails for an eye popping $1559. Upon initial inspection, I noticed the magwell was undersized. None of the magazines we had on hand would drop free and had to be forced into the gun, even with the bolt locked to the rear. One we began test firing it, after two magazines, the handguard began to rotate due to the handguard retaining screws beginning to loosen. Thankfully, I caught one before it fell into the sand. None of the handguard screws had any threadlocker and were only hand tight. Should you expect that from a $1500 AR pistol? No, but it was the result of poor quality control. As you've stated, you tore down complete uppers that were barely finger tight. When things like that happen, good luck finding the torque spec for proprietary parts used by the manufacturer.

    This is a great example of a variety of issues.

    Low to Zero qc by whoever wat responsible for the lower. Not sure if Springfield buy a completed, fully machined lower from a supplier? Or do they get a raw forging and fully machine/broach it themselves? Or a partially machined lower? At any rate, they should have some sort of inspection with "gauges" to determine if the lower is "in spec" for their use. A mag not fitting is pretty bad, as that is about the only thing the end user will actually install and remove from the gun...

    The lac of thread locker on the screws would be a good example of a bad build practice. Screws back out, especially when vibration is present. If all of the saint series of guns are lacking thread locker on the handguard screws it shows a fundamental lack of understanding on Springfield's part... I work on cars, and the mfg have slowly added thread locker to a lot of bolts in areas that they have not in the past. I feel like GM is basically making their cars stay together with thread locker these days, they have really embraced it.

    Sounds like Springfield has just tried to capitalize on a popular trend, braced pistol ar15 variants, and has not bothered to do their homework to get it right. TBH, I have never handled a Springfield product that filled my heart with awe and my mind with want...
     
    Last edited:

    DAVE_M

    _________
    Rating - 100%
    32   0   0
    Apr 17, 2009
    8,288
    36
    ________
    This is a great example of a variety of issues.

    Low to Zero qc by whoever wat responsible for the lower. Not sure if Springfield buy a completed, fully machined lower from a supplier? Or do they get a raw forging and fully machine/broach it themselves? Or a partially machined lower? At any rate, they should have some sort of inspection with "gauges" to determine if the lower is "in spec" for their use. A mag not fitting is pretty bad, as that is about the only thing the end user will actually install and remove from the gun...

    The lac of thread locker on the screws would be a good example of a bad build practice. Screws back out, especially when vibration is present. If all of the saint series of guns are lacking thread locker on the handguard screws it shows a fundamental lack of understanding on Springfield's part... I work on cars, and the mfg have slowly added thread locker to aot of bolts. I feel like GM is basically making their cars stay together with thread locker these days, they have really embraced it.

    Sounds like Springfield has just tried to capitalize on a popular trend, braced pistol ar15 variants, and has not bothered to do their homework to get it right. TBH, I have never handled a Springfield product that filled my heart with awe and my mind with want...

    You’re right on the mark.

    Springfield entered the AR market very late in the game. While some companies like Springfield do have the manufacturing capabilities that others don’t, they are outsourcing parts just like every other AR manufacturer. There a dozen larger outfits making bolts and carriers. Toolcraft, AO Precision, Azimuth, and Microbest are just a few. While they may source bolts and carriers from an OEM, they are likely piecing them together in house. This is when you see issues with gas keys, gas key screws, gas rings, cam pins, firing pins, etc. Even so, larger companies are not checking every rifle that goes out the door with the same scrutiny as some of the higher tier manufacturers are doing. Springfield Armory does test fire their rifles, with a single round. Other manufacturers at least run a short full auto burst through their uppers.

    Although AR-15’s are not even remotely as difficult to piece together as AK’s or even bolt guns, there is still a lot that goes into them. They are far from Lego bricks.
     
    Top Bottom