I was putting a barrel into an upper last night and forgot to put the aeroshell grease I usually wipe all over the barrel extension and inside of the receiver.  I'm using an aero precision m4e1 enhanced upper which says to torque the barrel to 50 ft lbs instead of the usual somewhere before 80.  When I started torquing the barrel on the damn barrel nut wrench sheared one of the nubs off and is now useless, so I can't remove the barrel.  I think the barrel nut wrench sheared when the torque wrench 'clicked' at the 50 mark but I'm not sure.

Any advice?  How important is greasing the barrel extension?  I liberally greased the threads of the barrel nut but not the extension itself.  Also, what about my torque?  The receiver and nut don't need to be timed with the gas hole.  Am I good to go or should I remove and retorque?

If you are worried about it, then remove, grease and re-install.  Myself, I have a couple of them around here that I have not put grease on the extension and they have been reliable, good shooting rifles, but it comes down to "Are you going to be thinking about each time you shoot it?"  

If you will be thinking about it all the time, then redo.

Do you plan removing the barrel from the upper several times? If not then I wouldn't worry about. If so then grease it up.

Call Aero, they know that they had a "soft" batch of those wrenches. They sent me two just in case, never had a problem again.

Putting grease on the exterior of the barrel extension does not have any affect on the torque applied to the barrel nut with one exception. The rim of the barrel extension (the surface that faces the muzzle end of the barrel) that contacts the inside flange of the barrel nut should be greased along with the threads. Friction during torquing not only comes from the threads but also from the shearing forces that occur where the rim of the barrel nut contact the barrel extension flange. Depending on the materials/finish of barrel nut and flange, two dry surfaces contacting each other during a shear force load could affect torque depending on how fine you want to split hairs.



If you think your torque wrench clicked at 50 it should be fine. As long as your torque wrench was perpendicular to your barrel nut wrench all should be well. Remember, spec is 30 to 80. Greasing the exterior of the barrel extension could act as an anti-seize for future removal of the barrel. That is all I can think of.....

Thanks everyone!  This puts my mind at ease.  I don't plan on removing the barrel for any reason.  The threads did receive a good amount of grease and I'm definitely in the mil spec area of 30-80 foot pounds.  It's good to know that some of you have been shooting without the grease.   I'm going to take it to the range and put a hundred or so rounds down range.  If there's anything wrong I'll remove the barrel and redo the whole thing otherwise I'm leaving it as it is.  I'll still contact Aero for that replacement wrench.

For what its worth, I just installed a barrel on a Aero M4E1 and stripped a nub off the wrench too at 50lbs of torque. I'm sure if you let them know they'll send you a replacement.

The main point off the lube is to prevent galling of the receiver threads.

Grease goes on the threads not the extension.....

Normally you torque the barrel nut to position and loosen 2 times and on the third time tightening leave it.  

No need to grease the extension to receiver. Just the threads.

In NM, you likely won't have to worry. If you were in a more humid environment, especially near the ocean, one of the benefits of grease is the prevention of the galvanic corrosion that tends to happen when you mate two different types of metals. Not the primary reason for using grease, but it is still a concern in wetter climates.

It sometimes helps get the extension into the upper - and it doesn't hurt to do that.

OP, as long as your barrel nut is aligned properly, there's no problem with having gone all the way to 80 ft-lbs torquing the nut.  If you "need" to remove the barrel, and if you're not too worried about having to replace a $10-$12 barrel nut, a pipe wrench works just fine for that.  

But do contact Aero about their wrench, because it shouldn't have failed.  I've buggered more than one barrel nut with a GI barrel nut wrench, and the wrench is still fine.

I had one torque at 30lbs as it lined up.  Never had a problem.  You're probably good.