Temporary barrel / handguard on a STAG build

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essorx

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Hi folks,

Out of curiosity, what are the impact of an improperly torqued barrel ?

Background is that I should have all the parts for my STAG-10 build by tomorrow and I'd love to take it out to the range over the week-end. The catch is, I only have a temporary/used barrel / handguard, the final ones still being in the mail. I'll be putting maybe a box or two of ammo down the pipe. Should I still put anti-seize and torque the barrel to 40 lb.ft (or less, as wet thread require less torque to reach the same clamping pressure ?), or can I get away with snugging the barrel but not torquing it to spec ?

All in all, I'm more looking to do a function/cycle check of the action rather than a full precision calibration... any advice ?
 
You should absolutely torque it to spec. Why wouldn't you, too lazy to remove it or concerned about seizing? I'd rather deal with a stubborn barrel nut than have the headspace shift when the barrel nut creeps from being loose.
 
Make it tight, I've never used a torque wrench to build an upper and I've never had any issues.

Use a barrel vise or reaction rod to anchor the barrel and then tighten it, loosen a 1/4 turn, tighten it, loosen it a 1/4 turn then tighten it, then tighten it a little more if needed to line up for the nut so the gas tube can pass through if the barrel nut is of the type that needs to be aligned (not all do depending on the forend you pick).

Tight, just remember that you're receiver threads are aluminum and the barrel socket is fairly thin so no snipes or 18 inch long wrenches. And don't just put your receiver in a vise, there have been plenty of guys that learned the hard way that an aluminum receiver is not designed to take a lot of torsional forces. Lots of guys will tell you that they do it all the time but there's definitely a better way.

I'm sure someone will be along shortly with a proper torque spec.

If it's loose the barrel will be able to wiggle which will affect accuracy. You'll be able to tell right away if it's not tight enough.

Jube said:
You should absolutely torque it to spec. Why wouldn't you, too lazy to remove it or concerned about seizing? I'd rather deal with a stubborn barrel nut than have the headspace shift when the barrel nut creeps from being loose.
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There is no headspace shift, the bolt locks into the barrel extension creating the headspace, that is why there is no adjustment for headspace on an AR. I've been told by a very experienced AR armourer that if it chambers cleanly and the bolt locks up it's good, no need to ever check headspace on an AR. Bolts are lapped to ensure even pressure on the lugs, not to set headspace.
This is all assuming that the chamber was cut correctly and that the extension was also correctly installed.

BeerBaron said:
Torque it. I have had barrels come loose with no major catastrophes, but why would you risk it?
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How does the nut come loose when the gas tube stops it from moving?
Unless of course you were using a forend that uses it's own nut that doesn't require alignment, even then if it was tightened by someone with enough strength to move it past hand tight it's probably not coming loose. Of course I give it more than that but it's not coming loose if it's only 30 Lb-ft instead of 60 Lb-ft.
 
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cr5 said:
If it's loose the barrel will be able to wiggle which will affect accuracy. You'll be able to tell right away if it's not tight enough.
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As I mentioned, I don't care about accuracy, the barrel and handguard are going to be replaced next week.
 
you know at risk of being an #######, but it never fails to amaze me some of the questions here. there is an explotion happening 6-10" from your face in the chamber of a rifle. should I put the bbl on correctly, or just hand tighten it? only wana shoot a few boxes no biggie. 50,000 plus preasure happening there infront of your face. don't care if its accurate or not. dam man do it right and be done why risk your face and even life perhaps
 
You could shoot it without a barrel nut and it still won't blow up. You could clamp the barrel and extension in a vise, load a round and as long as you index the bolt lugs properly closed, hit the firing pin with a hammer and it won't blow up.

The barrel extension to the barrel is the load bearing piece in the pie. The bolt provides the lockup. Loosening your barrel nut has absolutely nothing to do with headspace. Loosening the barrel out of the extension has everything to do with headspace.

Oh and it wasn't a stupid question, but you did get some less than spectacular answers.
 
Beater said:
you know at risk of being an #######, but it never fails to amaze me some of the questions here. there is an explotion happening 6-10" from your face in the chamber of a rifle. should I put the bbl on correctly, or just hand tighten it? only wana shoot a few boxes no biggie. 50,000 plus preasure happening there infront of your face. don't care if its accurate or not. dam man do it right and be done why risk your face and even life perhaps
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You are 100% correct, there is a high pressure explosion very close to your face. Proper assembly is important, All I'm saying is that you don't need to go to a specific torque value, the barrel should be very tight, I'm assuming this guy has a barrel wrench and at least enough sense to know that holding the receiver between his knees and turning it as tight as he can with his hands is not good enough.

I guess that I need to stop assuming people have some sense and make sure before I give simple answers.

essorx said:
As I mentioned, I don't care about accuracy, the barrel and handguard are going to be replaced next week.
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I'm slowly getting the feeling you don't know enough about this to be doing it alone.
You should care, if it's just for a week it should be tight for that week or you should just wait till you are prepared to do it right.

Do you have a proper barrel nut wrench? Do you have a way to hold the barrel in a vise so it doesn't turn? Or were you just going to wrap the receiver in a rag and stick it in a vise? Or even worse do it as I described above?

Assembling a rifle is not something for people to just try. There's no participation award at the end for trying, it's a ride in an ambulance for you and/or someone that was too close to you.
If you've never done it before there are lots of youtube videos that can help you. If you don't have the right tools then take it somewhere to have a professional assemble it for you. It's not worth risking ruining your receiver or worse.
 
Beater said:
you know at risk of being an #######, but it never fails to amaze me some of the questions here. there is an explotion happening 6-10" from your face in the chamber of a rifle. should I put the bbl on correctly, or just hand tighten it? only wana shoot a few boxes no biggie. 50,000 plus preasure happening there infront of your face. don't care if its accurate or not. dam man do it right and be done why risk your face and even life perhaps
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I remember why I don't post here more often, always same jack*ss comment like that. The pressure is taken care of by the chamber/barrel when the BCG locked to the the barrel, the barrel can't turn due to the locating pin and the nut itself can't rotate without rotating the whole handguard. Torquing the barrel nut only provide compression...

But whatever...
 
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cr5 said:
Do you have a proper barrel nut wrench?
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No, I'm gonna use the Force

[I'm not sorry, but this is the only kind of answer your patronizing comment deserve. You should have stopped to your previous comment which was actually valuable...]
 
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Sqr said:
Always torque it and use mil grease.
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people have been very coy as to providing any actual torque spec numbers (or better, actualy clamping load) and condition which apply to this torque spec (eg. dry or wet thread, as the clamping load will be higher on wet thread due to lower friction at equivalent torque)...
 
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essorx said:
No, I'm gonna use the Force

[I'm not sorry, but this is the only kind of answer your patronizing comment deserve. You should have stopped to your previous comment which was actually valuable...]
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Sorry, but your comments made me question your competence.
If you have the tools then why the question? Just tighten the damn barrel and go shoot. Why ask if it needs to be tight? Of course it needs to be tight.

Do or do not... there is no try.


You've been a member long enough I'm sure you've been frustrated by the stupid questions asked on here some days. So why add to them?

I'm tired of the stupid questions but I also can't stand the thought of standing by and watching while someone does something that could hurt or kill themselves.
I'm trying to comment less because of threads like this.
 
cr5 said:
Sorry, but your comments made me question your competence.
If you have the tools then why the question? Just tighten the damn barrel and go shoot. Why ask if it needs to be tight? Of course it needs to be tight.

Do or do not... there is no try.


You've been a member long enough I'm sure you've been frustrated by the stupid questions asked on here some days. So why add to them?

I'm tired of the stupid questions but I also can't stand the thought of standing by and watching while someone does something that could hurt or kill themselves.
I'm trying to comment less because of threads like this.
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could not have said it better myself. X2
 
essorx said:
people have been very coy as to providing any actual torque spec numbers (or better, actualy clamping load) and condition which apply to this torque spec (eg. dry or wet thread, as the clamping load will be higher on wet thread due to lower friction at equivalent torque)...
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See, now you go and say something intelligent, you're a very hard man to read.

I don't use a torque spec, I use the force to tell me when it's tight enough, but if you need one try google.

And there was never a need or expectation from me for you to be sorry for your reply, I was not offended, only confused by your questions and replies, wording maybe? Maybe you meant something else and we misinterpreted?

Or did you just read that stuff about torques somewhere else and copy paste it? :p
 
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I’ve done several and always tourqe to 35- 40 ft lbs.
I’ve read that the specs are 35-80 ft lbs.

I’ve also did one by hand , just using the armorers wrench, it ended up at 38 ft lbs.( I checked)
In the end you should be able to do it without a tourqe wrench but I still like to use one.
And I’ve been using copper anti seize, as it’s what was available to me at the time.
 
45C said:
I’ve done several and always tourqe to 35- 40 ft lbs.
I’ve read that the specs are 35-80 ft lbs.

I’ve also did one by hand , just using the armorers wrench, it ended up at 38 ft lbs.( I checked)
In the end you should be able to do it without a tourqe wrench but I still like to use one.
And I’ve been using copper anti seize, as it’s what was available to me at the time.
Click to expand...

Use the little packs of dark grey grease that comes with brake pads.
 
Not torquing your barrel nut down you run the risk of it coming loose and the barrel popping out, even if the barrel is out just a few millimeter your bolt might get stuck, happened to me once while I was racking an upper without an round in the chamber while test fitting an upper. You can only imagine what would happen if there was a live round in the chamber.

Get yourself a torque wrench first, even if you meant to swap out the barrel later on, torquing the barrel nut to proper specs takes just a few seconds, it doesn't take anymore effort to removed a torqued barrel nut.
 
cr5 said:
There is no headspace shift, the bolt locks into the barrel extension creating the headspace, that is why there is no adjustment for headspace on an AR. I've been told by a very experienced AR armourer that if it chambers cleanly and the bolt locks up it's good, no need to ever check headspace on an AR. Bolts are lapped to ensure even pressure on the lugs, not to set headspace.
This is all assuming that the chamber was cut correctly and that the extension was also correctly installed.
Click to expand...

I know that's how the lockup works and the theory behind it, but there are go/no-go gauges for a reason. Don't be telling folks that they can do this and it's safe; it's a semi-auto and things can change between rounds when threaded parts are not torqued down. It's unlikely, but I've seen some pretty strange things happen even with factory-assembled firearms when corners get cut.
 
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