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KYGun
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Posted: 1/12/2013 12:02:30 AM
I tightened an AR barrel nut as much and as far as it would go with hand pressure and using a DPMS wrench, but did not use a vice or torque wrench. Is it anyone's opinion that as long as I tightened this pretty good by hand with wrench, and got the gas tube through and lined the way it should be thay it'll be ok? I mean the gas tube is keeping he nut from ever lossening because it holds it steady. What do you think? Are 35 pound torquings of barrel nuts overated?
goldeyeslayer
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Posted: 1/12/2013 12:18:34 AM
35 is a minium and the specs are not overrated. do it right, or there will be problems later
You look like the most normal person on the planet, or a serial killer. I can't decide. Either way, rock on.- Dan_Gray
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Shooter62
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Posted: 1/12/2013 1:00:02 AM
[Last Edit: 1/12/2013 1:01:54 AM by Shooter62]
if you got it as "far as it would go" using a barrel nut wrench you should be GTG.
(unless you're REALLY WIMPY) ETA: 35 FT LBS isn't very much.
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Srconlee
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Posted: 1/12/2013 1:35:37 AM
I agree with shooter62 the YHM barrel nut I just put on didn't have a torque spec they literally just said hand tighten and then tighten with wrench to the next gas tube hole and your good to go. Now I did have a vise and I couldn't imagine being able to tighten that nut even that far without one it took some elbow grease. So I would recommend borrowing a friends vice to make sure you got the nut tight enough as far as actually using a torque wrench I think your fine. But remember if that barrel nut isn't tight (and it can be loose without you being able to wiggle it) You will sacrifice accuracy even barrel movements in the 1/10th of a mm will cause you to be way off target at 100-200 yards.
PR361
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Posted: 1/12/2013 9:06:45 AM
[Last Edit: 1/12/2013 9:11:27 AM by PR361]
I've built a pretty good handful with friends and never bothered with a torque wrench, The range is pretty broad, 35-80 Footpounds. Never had a problem.

Just remember to tighten, loosen, tighten, loosen, before the final tighten. Use a grease to prevent thread gaulling.

My current Armalite was assembled with a WOA National Match Barrel using the "Three Grunt" method in 2008 and routinely shoots one hole groups at 100 yards. So far it hasn't noticed I didn't torque it to spec.....

YMMV



ETA: Just reread the OP and realized you said " No Vice".

Makes me go "Hmmmmmm" ....not sure you can get there without a vice. Are you talking about just holding the reciever in your hand?

If so, I seriously doubt anyone has the grip strength to tourque to 35+FP

Really need a vice to install a barrel.
Eagle Scout
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Posted: 1/12/2013 9:30:53 AM
without a vice... you probably are shy of or right at 30 lbs.

I recently installed a barrel with a vice and wrench but the vice was not mounted to a bench... I barely was able to get 40 lbs with the vice trying to roll all over. i was doing my best to hold the vice and the wrench...not sure how anyone could get appropriate torque without a vice. checkout the recent review of steel and brass cased ammo that had 2 guns with lightly torqued barrel nuts, accuracy was absolute poo before they found the problem.
dfariswheel
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Posted: 1/12/2013 3:54:48 PM
As above the minimum torque limit is for a good reason. The nut may not unscrew because of the gas tube, but it won't be tight enough to prevent the barrel from vibrating incorrectly and ruining accuracy.

There's a very specific technique of properly installing an AR barrel and if you want good results, you need to follow it.

First, coat the threads with an anti-seize compound. Some people use grease, but an actual anti-seize is better.
Choose one that DOES NOT CONTAIN GRAPHITE. Graphite damages aluminum.

Screw the nut on and torque it down to at least the minimum.
BACK IT OFF and re-tighten again, back it off and tighten to the minimum a third time.
This tightening and loosening process mates the threads on the nut and receiver, and prevents odd vibrations.

Once the nut is tight the last time, check for where the clearance is for the gas tube.
Unless the nut is way off, just tighten the nut until the gas tube will pass through.
If the nut is way off, just loosen and tighten the nut repeatedly until it gets close enough to allow torquing it until the tube will pass.
Like tightening a bolt tightly, every time you tighten the nut, it will screw on just a little farther from the stressing of the threads.
Usually you don't have to do this and you can just tighten the nut until the tube clears.

All this prevents the barrel from loosening and allowing the loose barrel to destroy accuracy.
A slightly loose barrel never shoots good, and unless you have at least the minimum torque on the nut, the barrel will loosen sooner or later.

If necessary, check with one of the Rental Land type rental places to see if you can rent a torque wrench and a large bench vise.
Note that an AR receiver vise IS NOT a bench vise. It's a special holder to hold the receiver while working on it and it fits into a bench vise.
Possibly you can borrow an AR receiver vise to hold the receiver while you torque the nut.
People on this site may be willing to rent you one.

Like all gunsmithing, you can often get by without having to buy a lot of expensive tools, but there's always at least a few you just cannot do a job without.
In this case a real AR receiver vise and a torque wrench.
Without these you're going to either damage the receiver, or have a rifle that won't shoot well.
2sigs
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Posted: 1/12/2013 4:42:42 PM
LOTS of good info here so no need to reiterate, However when someone says the gas tube is lined up what's their definition of "Lined up"?

I'll not go into that as there is that info found easily with our search tool here or another, I prefer startpage.com

Use a Gas tube guide or #16 drill bit to verify alignment as an easy solution.

Some inexperienced builders will say "bah I do it this way and it's right!"

I've found gas key/tube interaction so far out that I can not believe anyone would think it right, but it still works, don't make it right in my book.
I find that by installing the charge handle and carrier without bolt assembly into upper and sliding it on and off the gas tube you will be able to feel the carrier bump if not 100% aligned
This is assuming the gas tube was installed correctly and is straight as designed.

Enough with the rant and yes even a bent gas tube installed poorly will function, Good thing God looks out for fools and idiots as they say

Be safe everyone and No Comply
Dano523
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Posted: 1/12/2013 8:21:18 PM
Originally Posted By KYGun:
I tightened an AR barrel nut as much and as far as it would go with hand pressure and using a DPMS wrench, but did not use a vice or torque wrench. Is it anyone's opinion that as long as I tightened this pretty good by hand with wrench, and got the gas tube through and lined the way it should be thay it'll be ok? I mean the gas tube is keeping he nut from ever lossening because it holds it steady. What do you think? Are 35 pound torquings of barrel nuts overated?


You can run it as it, but going to find that down the line, the barrel is going to end up loose in the upper receiver, and just spraying.

So on that note, threads and mating surfaces of the front of the barrel extension to the barrel nut litho greased, take the nut to 30lbs back it off, do it again,back off, then go for the next hole without going over 80ft of torque on the third torque. The first two torques mate everything in, and via that and the grease, makes sure that you are not getting a false torque reading on the final torque.

Posted By PlaymoreMinds:

'Twas not the <cough> sweet and innocent <cough> PlaymoreMinds...

<---skips away in frilly skirts to Candyland, leaving gutters and snorkels FAR behind.