I just put on a new barrel from BCM into an upper BCM, I had to torque the barrel to 55 ponds to get the tube aligned was that to much?

You should just have to set the wrench to 30ft lbs, then tighten it with the torque, loosen it not with the torque and repeat 3 times. Go up in 2lb increments and you should end somewhere around 32 to 36ft lbs.

I assume you're talking about the barrel nut. You're good. High end is 85 ft/lb if I remember right

No......that is some made up number....I already posted straight from the armorers book how you do it. The USGI armorers book....you don't want to go past 40ft lbs at the max...

You tighten to the MINIMUM torque which is 30lbs, then keep turning until the slot and hole is lined up for the tube.

Thats it, nothing else to it. The is no "magic" specified torque like on a car engine parts... One's whose bolt heads can be anywhere at any angle and need to be consistent to avoid undue pressure and warping. A barrel nut is nothing like that and needs to be aligned, not torqued. The min value is simply to ensure its doesnt get loose and wiggle.

Does the manual tell you what to do when you can't get the gas tube in at that torque value? I guess if you have an unlimited supply of barrel nuts you can keep trying until you find the perfect combination.

lol yeah its an armorers manual......I am not going through this whole thing again..... "Search" .....its probably on 2nd or 3rd page.....and I have assembled just say minimum 30+ barrels to receivers and I have never gone over 40ft lbs, and amazingly just by using the manual.

Let me guess how many of you actually have these in your toolbox.

BARREL NUT SHIMS!!!!!! WHAT

3 Pack of 0.001" thick shims for use in the installation of AR-15 rifle barrels.

Use these shims to obtain correct barrel nut allignment within the correct barrel nut torque specifications.

Instructions are included.

It seems to me some of us are having a hard time comprehending the process which has been outlined clearly. But i hope the rest get the info they need. And id point out, zero of the so called top tier arfcom manufacturers shim barrels.... So... Think about that if youre on the fence...

I have a stack of shims in my toolbox and have not used one....I am pointing out in the manual itself it says if ...the other techniques to correct do not work...use shims.

I bet most companies don't use vice grips and green electrical tape, and just say torque 30 to 80 whatever!

Also WTF would it matter if you shimmed it .001????? Are you kidding me ..... I rather have the low torque tolerances on my barrel to receiver so that no amount of unnecessary cant would be put on my barrel causing any amount of offset in barrel alignment in those tolerances..

you referring to your self because the armourer's manual torque settings have clearly been published. Show me somewhere that 30-80 has been published in print by the military and not some randon link to another post on AR15.com!

TM 9-1005-319-23&P  0015-17

Figure 20. Torquing of Barrel Nut Assembly.

8. Engage threads of barrel nut assembly (19) with upper receiver assembly (11).

9. Using combination wrench (15) and torque wrench, torque barrel nut assembly (19) to 30 ft-lb (40.5
N-m). Torque is measured when both wrenches are used together.
NOTE
Performance of torquing procedure three times provides for a better thread fit and
prevents barrel nut from becoming loose. Do not use the torque wrench for loosening.

10. Make certain all three drive pins or the teeth on combination wrench are engaged with barrel nut
assembly (19). Loosen and repeat torque operation. Then loosen the barrel nut again.

11. ........CAUTION
Do not torque over 80 ft-lb (108 N-m) while tightening barrel nut assembly to next
hole, to allow for proper alignment of gas tube.
NOTE
Do not attempt to hold upper receiver assembly with pry bar; however, if barrel
assembly turns in holding fixture, a pry bar may be used through front sight
assembly base to help prevent barrel assembly from turning in holding fixture. Use
care not to distort or bend front sight assembly or retaining pins. Use "buddy
system" to hold pry bar.

12. Torque barrel nut assembly (19) again to 30 ft-lb (40.5 N-m) while maintaining sight alignment. Barrel
nut assembly may be tightened beyond 30 ft-lb (40.5 N-m) to align barrel nut assembly serrations for
proper gas tube clearance. Never loosen barrel nut assembly to align for gas tube clearance.

It still keeps mentioning 30 ft lbs not 30-80 its almost like they are saying hey dont go full retard and torque over 80 ft lbs! plus isn't that from a field manual and not an armorers manual?
field manuals are kinda like this!

Not saying its scientific but I have and every guy I know has.  Low side is hundreds of thousands of rounds down range.  No gun ever blew up or malfunctioned based on barrel nut torque.  Always start the torque at 30 after tightening and loosening process. Then index to next hole.  Will not profess it is the anal retentive usgi chapter and verse right way.  But it works.  It functions.  And not one single problem ever.  


 

The 23&P is an Army, Air Force and Navy Technical Manual dated November 2008. One of the posters above wanted to see where the 30 to 80 ft lbs had been published in print by the military, and this is one particular place where I've found it.  

As I posted, it does indeed say to torque to 30 (item 9), then loosen (item 10), then a caution not to exceed 80 ft lbs while tightening the barrel nut assembly to the next hole to allow for proper alignment of the gas tube. It all seems pretty straight-forward to me and I have no idea why this is such a big deal to some folks.

To the OP: 55 ft lbs is right about where you want to be and you're good to go!

Wrong. It is not some made up number, it comes right out of the 23&P, and 80 ft lbs is the max not 40.

You clearly have some strong opinions on the matter but you're giving poor advice in this instance. I don't expect to change your mind, but I think it's only fair to offer some additional information to folks out there with questions.

I read that quote as saying don't go over 80ft pounds of torque. Start at 30 and tighten to align to next hole. All of my builds went to exactly 35-36 ft pounds of torque and I stopped right there. Never had an issue of the nut coming loose or anything else.

I don't see where it says even if you're aligned at 40 keep going up to 80 ft pounds of torque. So IMO while it could be possible to get to a max of 80 ft pounds of torque to align to the next hole, if you hit the sweet spot every time as I have so far at 35-36 or even 45 ft pounds, you should be just fine with no need to go any higher in torque.

My Son in the Army has even confirmed this for me about a week ago.

As already mentioned everyone has an opinion on this, this is what works for me and I'll continue to keep doing this. What works for others is what works for them. But in no way as I have read the documents and inquired does it say to go to 80 ft pounds every single time. If you hit the spot where it aligned between those numbers, that should work just fine.

This.  Except that it is helpful to re-torque to 30 ft.lb. prior to final tube alignment.  All threads benefit from this.



 

80 ft lbs has always been a not to exceed value (that I will never visit).

Perfectly stated, you are absolutely correct.

I just finished my first build and I have the YHM Free Float rail with their barrel nut and it was perfectly aligned at the gas tube hole when it was hand tight. Between that and half way to the next hole it was already 50lb and it was at least 80 by the next hole. There was nothing in between. I loosened and retightened half a dozen times to make sure but I ended up leaving it after getting the nut in place. Everything lines up perfect but I am worried about the amount of torque on there. Now i'm thinking about those shims and redoing it to the previous hole???

Sounds a good candidate to shim.
Use moly-fortified grease on those threads.

I used Aeroshell.

Here's another newb question (sorry to hijack the thread)...
Is there supposed to be a gap between the barrel nut and the upper or is the barrel nut supposed to be snugged up tight against it?  I couldn't find any close up pics online for reference.


http://i44.tinypic.com/2prsavo.jpg

I don't use that set up, but if you have no gap you would need plenty of sh!thouse luck to get alignment for your gas tube with the nut meeting the receiver.
A gap would be both normal and necessary.

Ahh of course. Makes sense.

I'm saying based on my real life experience you are fine, I'm willing to bet.  Unless you are using some cheap 6061 AL upper.

 

I used shims to get the torque at 34.5 pounds

That's a good solution.

Some don't know that they're available.
Some have a hard time wrapping their heads around the concept.

Before it was at 75 pounds to me that was to close to the 80 and I didn't want any problems.  I tried two barrel nuts with the same high torque.  Shooter mcgavern gave me the sight to order the shims and the worked really well.

You're good to go.