When I install barrel nuts I torque them on and off a few times after using some grease on the threads then torque them using a snap-on torque wrench to there final torque. Well while installing a noveske barrel I had to use the max range of 80ft lbs to align the gas tube. This upper has had 2 previous barrel nuts installed with different handguards in the past and I have never had to go over 50ft lbs on a build. Anyone have ill effects using max torque value?

You'll likely no have any function issues, but if absolute accuracy is a concern then it can be a detriment.  The benchrest guys tend to stay as low as they can get away with.  The thought is that the higher the torque the greater the potential is for distortion at the barrel extension.  This is also why they always lap their uppers.  By removing even the slightest imperfections from the face of the upper the interface with the barrel extension flange is perfect, and therefore distortion minimized.  The lapping can also be used to reduce the torque necessary as there is a minute delay in the contact between the upper and the extension flange, thus allowing the nut to rotate slightly further at any particular torque setting. If it concerns you lap the upper and reap all the benifits thereof.  It's easy and the tool is about $35, plus a bit more for the compound.  I do all my uppers before I assemble them, using the 600 grip compound.  It goes slow and allows me more control compared to 300 or 200.

Thanks, like I said this is a first for me as I haven't had to go that high. I'll pull it apart and try that. It would be good information if anyone has had to torque a barrel nut to 80 ft lbs and the gun still shot well or in fact shot like crap and then made adjustments and had different results.

It would appear there is no longer a max torque.
The TM now just says go to 30 ft/lbs and then to the next alignment if needed.

Which edition?  I haven't seen that update yet.

The change date would need to be sort of recent. Last couple years at earliest. I'm requesting a PDF of the latest rev right now.

So has anyone actually seen negative results using the upper echelon in torque?

If it's done right, there should be no issues with using the "maximum allowable" torque.  It IS, after all, "allowable," right/

Torque on the barrel nut should only affect the front of the upper receiver and the barrel nut.  80 ft/lb is the top end, but there have been plenty of folks posting here who've said "F-it, I'm not stating over just because I had to go to 90 ft/lb," without coming back and saying "I borked my gun by over torquing the barrel nut."  And I'm pretty sure they would have come back and complained...  

Lap the front of the receiver with the Brownell's tool or by hand on a flat surface with 400 grit "wet or dry" paper.  Wet the paper with light oil such as WD-40.  Only removing a few thousandths from the receiver will allow gas tube alignment at a lower torque.

Nov 2008
http://www.kdeguns.com/ar-manual/M4%2016%2023Pchange8.pdf

The caution at the top of page 0015-17 (which includes step 12, torquing the barrel nut) says
It's still "30-80 ft/lb"...

I do not think you could ever distort a barrel extension putting on a barrel nut.  The upper would be fubar before that happens!

Nice avatar! It is a noveske barrel I will be using so I am concerned about accuracy issues on this one. I may shoot it as is and do a few rounds for groups before pulling it apart just to see if there is any change in accuracy.

I'd go with the Brownell's tool, which will also true up the face of the upper, rather than just using flat sand paper.  It may only take evening out the anodizing on the face of the upper to change the torque needed to line up a barrel nut notch.

It's important to know that every barrel nut is potentially unique enough that it could thread on the upper differently enough to cause a rather large difference in how much torque is required to line up a gas tube notch.  If you run into this kind of thing, you could simply change barrel nuts and have a completely different fit, with a completely different torque required.  (Of course "simply changing the barrel nut" ain't always exactly "simple," but the principle is there.)

Its not for one I would have to get a new one from Midwest industries as I have there ssk keymod rail and it uses a proprietary barrel nut. And the noveske barrel  has pinned gas block.

Missed that.