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So I have taken this barrel on and off about 10-12 times throughout its life & now it is acting up.  I first got it, torqued it too low & came loose after about 1,000rds.  Installed it again-took about 4-5 tourques to get the holes aligned.  Shot about another 500rd though it then decided to send it to Adco to get some work done.  Got it back a week ago and got around to installing it again yesterday and now I have this:  cleaned & re-aplied some dry lube to the threads, 1st tourque was at 30 ft/lbs.  Wanted it on the higher end, so I tried the next hole.  No go, got to 80 & was not aligned.  Loosend and tried again.  2nd try was at about 24-30 ft/lbs, so I figured I would try 80 ft/lbs one more time.  No go AGAIN.  So the last time I put it on the 1st hole looked at 26 ft/lbs and the 2nd hole I am guessing will be at 90 ft/lbs (which I did not do).  What should it do?  Should I keep tourqing until I get the 2nd hole at 80 ft/lbs, or go low.  If it makes any difference I have a Vlto MUR which I believe has a high tolerance.  If I am staying within the tourque threshold is there any danger of fucking up the threades or stregth of the upper or barrel extension ot barrel nut?

Also I forgot to mention the second time I torqued it on the right way it was at 60 ft/lbs before I sent it to Adco

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Did you remove all the old grease before you started trying to install the barrel again?  The procedure is not just "get it to 30 then crank it to the next notch," even adding "without going over 80 ft lbs."  Here is the correct procedure:

First, with a clean upper and nut, apply the appropriate anti-seize grease, such as AeroShell 33MS, which meets the same MIL-G standard as is called for by the M16 TM.

Install the barrel and torque the barrel nut to 30 ft/lbs.  Now back off the nut at least a couple of turns.

Torque the barrel nut to 30 ft/lbs (second time).  Now back off the nut at least a couple of turns.

Torque the barrel nut to 30 ft/lbs (third time).  Gently and slowly add torque to bring the next barrel nut notch in line with the gas tube hole without going over 80 ft/lbs.
If you get too close to 80, go ahead and back the nut off again and reengage.  It's OK to repeat the "go to 30 and stop" process many times.

Repeatedly threading the barrel nut onto the upper spreads the grease thoroughly, both on the upper and in the nut, and it helps seat the steel nut on the aluminum upper more smoothly and completely.  In this process, the right grease is very important, as it provides the appropriate amount of lubrication for the torquing process.  Using "any old grease" on the barrel nut will result in undefined performance-as in the nut could seize or loosen up.

Back off the nut

Thanks for that.  I did not remove the old grease and that could explain the dilema.  I will remove the old and re-apply new and keep doing the 30 ft/lbs tourqe until I get it right.  I used a dry rag to remove any grit or debris, but I guess I could be more thurough.  I am using Birchwood Moly Lube Dry Film.  Any ideas if I could have damaged anything?

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Highly unlikely that you hurt anything. Just clean it up, reapply the grease, and keep re-torquing until it lines up, between 30-80 lbs. I've had a couple where it took me a good 15-20 times of re-torquing before it finally lined up properly...

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thanks for all the post, but for those of u who said no to the moly lube dry film, why?

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I know this isn't my thread, but have a question related to what's being discussed. Can this aeroshell be found at local auto parts stores or does it have to be ordered? If it is order only, is there a similar product that can picked up at a local auto store? I was just getting ready to reassemble my rifle and was just going to use never-seize on the barrel nut. Now that I stumbled across this thread, I want to make sure I use the right product.

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Any decent grease will work just fine as long as it does not contain graphite.  No need to mail order anything special.

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Whent down to Autozone today to see what I could find.  By the way I got the barrel of and thuroughly inspected the threads (GTG).  I got so worried there for a while.  I had to clamp the Vice block to a foldable table because I don't have the vice or bech at my house.  I couldn't get good leverage because I was sitting on the table to hold it down.  I finally got it of.  Had to tap the wrench a couple times to get it loose, but its good.  Heard the ply wood table crack a couple times.  I just couldn't wait any longer to see the fait of my barrel.  I gota say if my barrel is fine after all the shit I have done to it, it must be pretty damn hard to fuck up the threads.  anyway, I found some Permatex Anti-Freeze Lube (aluminum, copper, & graphite blend) that can withstand heat to 1,600 degrees.  Sounded good, but held off because of what u said about no graphite.  Why is this?

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Graphite can encourage galvanic corrosion.  That's what happens when two different metals are held together with something between them that can act as an electrolyte.  Also graphite is itself an abrasive, so it can scour the anodizing on your upper.  Plus it is not "the right" stuff.  It IS important to use the right material, or a more common grease would have been specified.  The MIL-G grease specified in the TM serves several purposes, including preventing the barrel nut from seizing on the upper, assisting in establishing the correct torque, and transferring heat between the two parts.  It's not that expensive-you'll spend less than what two boxes of Winchester .223 cost to get 14 oz of the stuff.

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I just ordered the Aeroshell  33MS. I will use this grease in my current build. I'm just curious. I have the Brownells barrel assembly paste # 083-050-100. Is this paste appropriate for M16/AR15 barrel to receiver assembly?