M5 Barrel Nut Issues

[Knuckledragger]

Howdy again, all. So. My barrel finally came in today. Barely. Had a hole in the side of the box big enough for it to slide out, but it was in there alright. But that’s another story. 
 

  I'm trying to install my barrel and for the life of me, I can’t get the nut to line up at torque. Closest I get is what you see in the pic.

 

I’ve tried using the whole shim pack, none of them, and everything in between. I don’t particularly want to keep pushing the barrel nut out further, as I’m already going to hate the gap between the handguard and the upper receiver. 
 Aside from getting additional shims, do I have any options here?

Parts being used:

Ballistics Advantage 20” Heavy Barrel

Aero M5 upper (Not M5E1)

Aero M5 Enhanced M-LOK Gen 2 Handguard and barrel nut

 

Edited June 1, 2020 by Knuckledragger
Spelling

[Knuckledragger]

1 minute ago, Swiftab said:

Does that barrel nut only have one slot in it for the gas tube?

Negative. It has four. One every 90°

[jtallen83]

What are you shooting for on the torque? 

[Knuckledragger]

5 minutes ago, jtallen83 said:

What are you shooting for on the torque? 

65 ft lbs, per Aero

[jtallen83]

I do despise the shim method of clocking, I usually end up ruining shims when I stack to many ,  but you dance with who ya brung. I generally make sure I get past 35 ft lbs and then stop when it lines up, have to admit to not reading directions though, I just shoot for between 35 and 80. Persistence has always gotten me there, sometimes after buying more shims to replace what I jacked up going on and off so many times. 

[Knuckledragger]

2 minutes ago, jtallen83 said:

I do despise the shim method of clocking, I usually end up ruining shims when I stack to many ,  but you dance with who ya brung. I generally make sure I get past 35 ft lbs and then stop when it lines up, have to admit to not reading directions though, I just shoot for between 35 and 80. Persistence has always gotten me there, sometimes after buying more shims to replace what I jacked up going on and off so many times. 

I guess that’s where I’m at then. You don’t think 35-ish is too little for a .308?

Edited June 1, 2020 by Knuckledragger
Spelling. Again. Damn Autocorrect.

[jtallen83]

4 minutes ago, Knuckledragger said:

You don’t think 35-ish is too little for a .308?

I set the wrench at 35 then move up till it lines up, never had it hit right at 35 but I would be comfortable with it. Don't remember where I first saw that spec but pretty sure I learned it here. @98Z5V can confirm those numbers, or tell you I'm full of it, or both 

[Knuckledragger]

Ok. I’ll go back to the bunker and work with those numbers. Thanks @jtallen83

[DNP]

If you get it set 35 or above, shoot it a bit, it ain’t going anywhere. It can’t. 

[Anderson3754]

Do it the way jtallen83 mentioned.

I'll just add some of my opinions. The threads are all ready "seasoned" from several attempts to torque the barrel nut. Hand tighten the nut has tight as you can with out any barrel shims. You want something close to 45-50 degrees before tight.  Take your wrench and tighten the nut till the nut lines up to slip your gas tube through, you will have approx 45-60 ft lbs, Your Done. Should you go ever so slightly past your line up point for the gas tube, just back it off slightly till the gas tube lines up. Don't make to big a deal out of this. With having 4 positions on your barrel nut it is not that bad of a job. Now, when you hand tighten and your just past a lineup hole on the nut, add like a .010 shim and that will put you around 45 degrees before tight. Then tighten your barrel nut till your gas tube slides in.  Your Done.

 Also if past one of the lineup holes in the barrel nut you can add a shim to get your barrel nut back before lineup, or use a receiver facing tool  and you lap a few more thousands off of the receiver face. BUT you must be cautious when doing this, a couple of thousands will rotate that barrel nut alot,!!!!!, and you cannot keep getting medieval with the Face Lapping tool.

I'm going to assume you did use a suitable type of grease on the threads initially when you made several attempts to tighten the nut. This is where the term "seasoned" comes in, working the threads back and forth from very snug to lose 3-4 times prior to final tightening.  I don't use a torque wrench to do the tightening, I use a standard wrench applicable to the style of nut being tightened, then when done, I use the torque wrench to see what ft lbs torque I have applied, if I have a strong need to know what the torque value is. 

Anything over 45 ft lbs is fine. I do not like going over 60 ft lbs of final torque. 60 ft lbs of torque on the barrel nut will net very close to 300 ft lbs of clamping force, that for me is max. Your receiver threads are aluminum, not hard to over stretch (distort) them. This can be dependent on what type of grease is used    And the Grease Debate will never end.

Now that we have Reactions Bars, it is the tool that should be used in lieu of the nylon upper receiver fixtures. They have just way to much flex in the design. But if it is all you have use it.

This is not one of those things,...... If more torque is better, then too much is perfect......Hope it helps

Ah............ just looked at your photo, it looks like you have a Reaction Bar?

Regards

[Knuckledragger]

@Anderson3754 thanks for the info. Yes, I have a reaction bar, but I made the wrong choice and got an aluminum one because “Aluminum won’t mar your upper receiver like steel will”. It’ll also twist like wet spaghetti, apparently. I took a deep breath and walked away from the bench last night and promptly ordered a proper steel reaction rod. I also stumbled across Aero having M5E1 blem uppers on sale & ordered one of those, as well.

  In a short time, I’ll have the correct tool for the job, a better upper and more forgiving barrel nut to work with, no more damn gap between the handguard & receiver, and oh-gee-darn... a spare upper receiver that’ll undoubtedly morph into a 6.5 CM setup and eventually another complete rifle. Funny how that keeps happening, ain’t it?
 

  When I do start on that upper again, I’ll not be using that handguard/barrel nut combo, but I’ll definitely be using the technique you layed out. 
 

I agree with you on the fixture vs. reaction rod thing. I’m not comfortable torquing on an upper just supported by the pins. I’m probably overly cautious, but I break less poop that way. 

[Anderson3754]

7 hours ago, Knuckledragger said:

@Anderson3754 thanks for the info. Yes, I have a reaction bar, but I made the wrong choice and got an aluminum one because “Aluminum won’t mar your upper receiver like steel will”. It’ll also twist like wet spaghetti, apparently. I took a deep breath and walked away from the bench last night and promptly ordered a proper steel reaction rod. I also stumbled across Aero having M5E1 blem uppers on sale & ordered one of those, as well.

  In a short time, I’ll have the correct tool for the job, a better upper and more forgiving barrel nut to work with, no more damn gap between the handguard & receiver, and oh-gee-darn... a spare upper receiver that’ll undoubtedly morph into a 6.5 CM setup and eventually another complete rifle. Funny how that keeps happening, ain’t it?
 

  When I do start on that upper again, I’ll not be using that handguard/barrel nut combo, but I’ll definitely be using the technique you layed out. 
 

I agree with you on the fixture vs. reaction rod thing. I’m not comfortable torquing on an upper just supported by the pins. I’m probably overly cautious, but I break less poop that way. 

No problem happy to help.  I would think the aluminum Reaction Bar would be sufficiently strong enough to achieve the needed torque but maybe not, never having used one. The other thing is when your ready to try again pm me, and we can get together on the phone for a few minutes to help make sure it comes out correct.

Regards

[Knuckledragger]

@Anderson3754 that is much appreciated, and I’ll take you up on it. 
 The rod is not a solid piece but, for some ungodly reason, has the splined end attached to the body of the rod via a coiled pin. 😒

Not the most intelligent design I’ve run across. Had I known that from the outset, I wouldn’t have bothered purchasing it. A solid aluminum rod would have been just fine, like you said, but this thing is deflecting a good 15°+, and staying there. The pin deformed and pushed out to where I had to get one of my largest pin punches and beat it flat enough to slide the receiver off. 
   Normally with tools I’m a “buy once, cry once” kind of guy. I was more interested in the non-marring claim of the tool than the (admittedly very low) price. Lesson learned. 🤷‍♂️

[jtallen83]

5 hours ago, Knuckledragger said:

The rod is not a solid piece but, for some ungodly reason, has the splined end attached to the body of the rod via a coiled pin. 😒

Possibly there to fail before the aluminum? Cheaper to replace a pin than the tool.

[Knuckledragger]

2 hours ago, jtallen83 said:

Possibly there to fail before the aluminum? Cheaper to replace a pin than the tool.

In theory, maybe. The pin is deforming and pushing out, and at torque levels well below max for a barrel nut. I got lucky in that it pushed out the ejection port side rather than inboard, so I could pound it back in to get the receiver off the tool and the pin didn’t gouge the interior. 
  The theory makes sense, but in this case the body of the tool is extremely soft and the pin they chose to use is a coiled spring pin that is one hard mf’er. 
  The splines themselves look fine and not deformed at all. I think it’s a combination of questionable design, inferior material and/or heat treating on the tool body and a poor choice in the coiled spring pin. 

[98Z5V]

Got a picture of this thing, or a link to where you got it from?  Who makes this rod?

[Knuckledragger]

1 hour ago, 98Z5V said:

Got a picture of this thing, or a link to where you got it from?  Who makes this rod?

https://ar15discounts.com/products/presma-ar-10-barrel-vise-block-rod-black/
 

I’ll get out to the shop and take some pics where I had to beat the thing to get my upper off it. 

[98Z5V]

That thing, by description, isn't even up to handling the torque range of tightening a barrel nut, which is 30ft/lbs~80ft/lbs.

Not dinging you in any way - just stating, the spec that they stated:

.308 Barrel Vise Block Rod for .936” – AR-10 LR-308, Black.     SKU AV3

Really cool tool for working on your AR build.  This multi-use tool helps with ease of installation of barrel nuts without scratching the exterior. Also a great way to securely hold your AR’s upper receiver assembly for maintenance and upgrades.  Comes with carrying case/holder.

These tools are made to grip in a bench vise so that the rod is either vertical or horizontal. You then slide the upper receiver onto the reaction bar.  The splines on the front of the rod enter the into barrel extension for a secure hold and fit.  Ready for tuning, it’s that simple.

12″ in Length.  Color anodized.  Tips are 7075 Aluminum and base is 6061.  Will handle 70+ ft lbs of torque.

[Knuckledragger]

Agreed @98Z5V. This was definitely not the best investment I’ve made in tools.  Honestly, had it been made in one piece, it’d probably work just fine. Just another learning experience. Thankfully not an expensive lesson. 
   If I find someone who’s decent at TIGing aluminum, I might have them weld it up and then turn it on a lathe. Not high on the priority list, though. 

[Anderson3754]

So the nose is aluminum, or the whole assembly is aluminum ?

[Knuckledragger]

1 hour ago, Anderson3754 said:

So the nose is aluminum, or the whole assembly is aluminum ?

Whole assembly is aluminum. Supposedly 7075 for the tip and 6061for the body. No info on heat treating. 

[unforgiven]

On 6/2/2020 at 11:39 AM, Anderson3754 said:

Do it the way jtallen83 mentioned.

I'll just add some of my opinions. The threads are all ready "seasoned" from several attempts to torque the barrel nut. Hand tighten the nut has tight as you can with out any barrel shims. You want something close to 45-50 degrees before tight.  Take your wrench and tighten the nut till the nut lines up to slip your gas tube through, you will have approx 45-60 ft lbs, Your Done. Should you go ever so slightly past your line up point for the gas tube, just back it off slightly till the gas tube lines up. Don't make to big a deal out of this. With having 4 positions on your barrel nut it is not that bad of a job. Now, when you hand tighten and your just past a lineup hole on the nut, add like a .010 shim and that will put you around 45 degrees before tight. Then tighten your barrel nut till your gas tube slides in.  Your Done.

 Also if past one of the lineup holes in the barrel nut you can add a shim to get your barrel nut back before lineup, or use a receiver facing tool  and you lap a few more thousands off of the receiver face. BUT you must be cautious when doing this, a couple of thousands will rotate that barrel nut alot,!!!!!, and you cannot keep getting medieval with the Face Lapping tool.

I'm going to assume you did use a suitable type of grease on the threads initially when you made several attempts to tighten the nut. This is where the term "seasoned" comes in, working the threads back and forth from very snug to lose 3-4 times prior to final tightening.  I don't use a torque wrench to do the tightening, I use a standard wrench applicable to the style of nut being tightened, then when done, I use the torque wrench to see what ft lbs torque I have applied, if I have a strong need to know what the torque value is. 

Anything over 45 ft lbs is fine. I do not like going over 60 ft lbs of final torque. 60 ft lbs of torque on the barrel nut will net very close to 300 ft lbs of clamping force, that for me is max. Your receiver threads are aluminum, not hard to over stretch (distort) them. This can be dependent on what type of grease is used    And the Grease Debate will never end.

Now that we have Reactions Bars, it is the tool that should be used in lieu of the nylon upper receiver fixtures. They have just way to much flex in the design. But if it is all you have use it.

This is not one of those things,...... If more torque is better, then too much is perfect......Hope it helps

Ah............ just looked at your at photo, it looks like you have a Reaction Bar?

Regards

Great explanation brother 👍

[Anderson3754]

9 hours ago, unforgiven said:

Great explanation brother 👍

Thankyou.... don't mine helping someone out at all. The school of hard knocks is a good teacher, but sometimes expensive. We have here on this forum a wealth of information, theres no reason to keep it a secret.