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View Full Version : WHATS YOUR AVERAGE BARREL NUT TORQUE?


gemini1
01-22-2012, 4:00 PM
I just dis-assembled my upper. I was anticipating that the torque of my factory assembled upper would be around 50 or so, but I was surprice when I didn't hear the "click" of my torque wrench set at 50 when I loosened the barrel nut, my guess is it was just in the 40s.
So now I have a different barrel nut to use and was wondering if I should tighten it more than what it was?
Also, I removed the barrel from the upper receiver, I plan to have it re-profiled. Once I re-assemble it, do I need to worry about head space?

Thanks guys.

baih777
01-22-2012, 4:13 PM
Minimum. 30 ft lbs and then tighten more to align hole for the gas tube

McLarenRoss
01-22-2012, 4:14 PM
I just snug them then tighten to line up the gas tube hole.

steve92407
01-22-2012, 4:21 PM
50 pounds +or- 5 for gas tube alignment with antisieze.

shadow65
01-22-2012, 4:44 PM
50 lb.s average

CHS
01-22-2012, 4:48 PM
I tighten to 30, and then go just far enough to get the gas tube hole aligned.

The AR barrel nut doesn't need a lot of torque, and has a very large range of acceptable torque.

I've seen over-torquing as a problem WAAAAY more than under-torquing.

gemini1
01-22-2012, 6:59 PM
What about the head space? I think I read somewhere that if simply replacing a barrel nut to that of a free float type nut then no worries. But what if the barrel is pulled out of the receiver?

motorwerks
01-22-2012, 7:25 PM
What about the head space? I think I read somewhere that if simply replacing a barrel nut to that of a free float type nut then no worries. But what if the barrel is pulled out of the receiver?

It will be fine.


I start at 20, then loosen it, 25, loosen it, then to 30.... try and get to the next open slot. If I get to 50 and my wrench clicks and I haven't gotten to the next slot..... I pull it apart and start over.

Rusty Scabbard
01-22-2012, 8:15 PM
Head space is set by the barrel extension. The barrel nut torque won't affect it. If you're loosening an assembled one it may be high. But when putting a new one together use moly grease and tighten to torque and loosen a couple times so the fit settles in. Then go to 30 and tighten a bit more as needed to line up the gas tube clearance. My build felt like it was around 50 when the tube clearance lined up.

gemini1
01-22-2012, 8:42 PM
Would the grease used for the front bearing on our car work if I dont have moly grease?
By the way thanks for all your responses.

motorwerks
01-22-2012, 9:25 PM
Would the grease used for the front bearing on our car work if I dont have moly grease?
By the way thanks for all your responses.

I've used everything from anti-seize to phil wood grease for bike wheel bearings...... the anti-seize makes a damned mess, and the phil wood actually seems to work the best and cleans up well. The wheel bearing grease will work fine, although I'm sure someone with an engineering degree will prove me wrong.

FNH5-7
01-22-2012, 9:29 PM
What would be a negative effect of over tightning?

I've heard anywhere from 30 to 80 is good and you're not supposed to pass 80. Moly grease should be available in small packs. I've put together 3 uppers and I got enough grease left over for thousands of more uppers.

CHS
01-23-2012, 12:01 PM
What would be a negative effect of over tightning?

I've heard anywhere from 30 to 80 is good and you're not supposed to pass 80. Moly grease should be available in small packs. I've put together 3 uppers and I got enough grease left over for thousands of more uppers.

It starts putting strain on the receiver itself and can warp, causing POI shift.

bender152
01-23-2012, 12:16 PM
~50 ft/lbs... give or take a few lbs to align the gas tube.

I've also used bearing grease (a very light coat) when assembling my uppers.

digdug74
01-23-2012, 3:41 PM
30-80 ft lbs is what I've read as being the "spec" for barrel torque. Haven't experienced it personally but I've read that over torquing (like, way over torquing) can sheer off the barrel index pin. You can also warp or crack the upper (which I actually did do but that was my fault for forgetting to put the front pin in the action block before torquing down the barrel).

dieselpower
01-23-2012, 4:07 PM
Please search my TM9 links.....

oh and zero is acceptable in a pinch.... paracord is AMAZING stuff...LOL
http://i655.photobucket.com/albums/uu272/Wiringguy/nowrench.jpg

motorwerks
01-23-2012, 10:13 PM
Please search my TM9 links.....

oh and zero is acceptable in a pinch.... paracord is AMAZING stuff...LOL
http://i655.photobucket.com/albums/uu272/Wiringguy/nowrench.jpg

this picture cracks me up.... no ones ever been able to tell me how the barrel nut magically got past the gas tube and all 21 teeth on the barrel nut.... to the point of falling apart. It isn't possible.

CHS
01-24-2012, 7:47 AM
this picture cracks me up.... no ones ever been able to tell me how the barrel nut magically got past the gas tube and all 21 teeth on the barrel nut.... to the point of falling apart. It isn't possible.

Really? So it's impossible for a steel nut to strip aluminum threads?