AR build, torque wrench question

[weenpeen]

Sorry for the newb question, but this is my first build. Here's my question. I plan on purchasing this barrel
20" 1:7 or 1:8 twist chrome lined government profile barrel with standard height front sight base.
According to the description, it already has the barrel nut attached. From what I understand, you need a torque wrench when installing the barrel nut. If the barrel already had the nut attached do I even need a torque wrench at all? Thanks

 

[Hookeye]

All that means is the barrel nut comes with it.

It is placed between barrel collar and front sight (sight assembly is pinned after slipping barrel nut on).

You will still need to tighten it (barrel nut) to the upper receiver. It's just on there, like a key ring on a pencil..........your hands at either end of the pencil similar to the barrel collar and the front sight.

Pictures can be a bit misleading if never having seen one before.

If you booger the nut up and need to replace it, you will have to remove the front sight to get it off, add a new one.

No big deal.

 

[weenpeen]

Thank you very much for clarifying. That makes sense now.

 

[Hookeye]

My AR has the 11.5" bbl with 5.5" flashhider welded on. It also has a pinned front sight (standard).
My front sight assembly won't slide over the flashhider should I booger up the barrel nut and need to change it.
Nope.
I'd have to cut my FSB off to remove the nut.
Yankee hill used to make a 2 pc FSB.......that'd be the way to "restore" it.
Thankfully using a good wrench meant no problems with the barrel nut. I won't be taking it apart/changing my mind anyway.

 

[223 Gunner]

If you use an AR armors wrench, there is a square cut out to place a torque wrench in.
I have an "old school" armors wrench, if I didn't own one and needed to buy one today, I would buy the one made by Magpul


Link: Magpul AR-15 Armorers Wrench - MAG535 - Primary Arms

 

[Tyler-The-Piker]

ask Earl. He's the Charlie Daniels of the torque wrench

 

[sloughfoot]

I have built lots of AR rifles. I have never used a torque wrench. The things that have to line up are far more important than any specific torque setting. The gas tube has to line up.

 

[rob63]

I have built lots of AR rifles. I have never used a torque wrench. The things that have to line up are far more important than any specific torque setting. The gas tube has to line up.

I used to be a design engineer (BSME) working for the US Navy, many moons ago before my second career as a school librarian. It was not unusual to get a call from the people that put together the maintenance manuals asking for some specific number, such as a torque setting, to put in the manual. At this point in the product cycle we design engineers had already moved on to the next project and no longer had funding for whatever project the manuals were being written for, so we weren't going to spend a bunch of time figuring out the correct number. You could check the assembly drawings to see if by chance it had been specified on that, but usually such things were covered by some boilerplate note that left it up to the manufacturing people to do in accordance with whatever the standard practice was. That might sound crazy to some, but if the people in manufacturing were used to doing things a certain way it was better to only add specificity if something actually needed to be done in a certain way so that it would stand out on the assembly drawing. The result was that when we got the calls about something to put in the manuals we usually just made a swag.

Every time I see the torque range of 30-80 ft.lbs., it sure sounds like a swag to me. Maybe the numbers are really based on something, but that sure is a wide variance to put too much significance in them.

Something even funnier to me is that there are a bunch of youtube videos out there that make a really big deal about making sure you turn the torque wrench 90 degrees to the barrel wrench to make sure you aren't getting an "incorrect" torque reading. They have over-thought the whole thing; the old Colt and military manuals specifically say that the torque numbers are to be read when using both wrenches together. Either way, whether those torque numbers were just a swag or were actually based on something, the people turning their torque wrenches 90 degrees to the barrel wrench are out of spec.

 

[NyleRN]

This is why I prefer quality rail systems that come with a barrel nut that doesn't have t**ts that need lined up

 

[gregkl]

Every time I see the torque range of 30-80 ft.lbs., it sure sounds like a swag to me. Maybe the numbers are really based on something, but that sure is a wide variance to put too much significance in them.

I agree with this. A 50 ft/lb range means get it tight enough but don't brake the armorer's tool trying to get it as tight as you can and one turn tighter.

Though I still use a torque wrench because I have not done enough to be comfortable with winging it. But then again, I use a torque wrench whenever I work on a car.

 

[ruger44srh]

All the AR's I have assembled, I torque the barrel nut to 30 ft. lbs. at least 3 times to stretch the threads and squeeze the anti-seize. Then line up the next cut out on the nut

 

[Psode27]

This is why I prefer quality rail systems that come with a barrel nut that doesn't have t**ts that need lined up

Thats where I'm at, I feel like its a much better system. I'm pretty anal about details generally, though I dont over think the torque issue. I do use a torque wrench to make sure I'm at least in the ball park of correct though.

All the AR's I have assembled, I torque the barrel nut to 30 ft. lbs. at least 3 times to stretch the threads and squeeze the anti-seize. Then line up the next cut out on the nut

I'm not that great of a resource here, but there was a thread here a while back discouraging anti-seize with aluminum parts. Something about the graphite or something in it can cause aluminum to corrode. https://www.indianagunowners.com/forums/gunsmithing/408236-ar15-barrel-nut-grease-got-any-share.html while the chances may be minimal and not a big issue, I stick with grease.

 

[Doublehelix]

This is why I prefer quality rail systems that come with a barrel nut that doesn't have t**ts that need lined up

I am not sure if it is a "quality" rail system or not, but I just installed a Midwest Industries handguard, and it could have not have been easier. (I torqued the barrel nut to 40 ft lbs after 3 rounds of tightening/loosening.) The gas tube goes right over the top of the barrel nut, and there is nothing to line up. Easy peasy.

 

[bigelowe]

You get it as tight as you can and then I will give it a half turn more. Bwahahaha. ( taken from my old tool and die coworker )