# Ar lower build question



## THE JAMMER (Aug 1, 2005)

Jut finished my first ar lower build, and have a quesion. Where the heck do you find a torque wrench that measures in inch pounds to torque down the castle nut on the buffer tube, and eventually a barrel on an upper build.


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## Ready.Fire.Aim (Sep 22, 2009)

Inch pounds for the castle nut & barrel nut? 

35 ft-lbs is the min spec


The specs are as follows, in Colt's "M16A2 Rifles and Carbines Armorer/Depot Maintenance and Repair Manual - 2nd Edition - 1991: 

1. Install Detent and Spring. 

2. Screw Reciever Extension onto Reciever while depressing Detent and Tighten Reciever Extension. 
- RIFLE: Use Torque Wrench, Part No. 94162 with Wrench,Combination Part No. 62696 (GI M16 Armorer Wrench) to apply Torque of 35-39 lb-ft. 

- CARBINE/COMMANDO: Use Torque Wrench, Part No. 94162 with wrench, Part No. 62420 to apply Torque of 38-42 lb.-ft. 

WHEN REASSEMBLING CARBINE OR COMMANDO Rotate Reciever Extension clockwise until it is flush or below Receiver and holding Buffer Retainer in place. Buffer Retainer should be free to move up and down. Install Takedown Pin Detent and Spring. Position End Plate and tighten Nut. After the Reciever Extension Nut has been tightened, the End Plate is to be staked with a center punch to any two of the Staking Slots in the Reciever Extension Nut. (Diagram shows upsetting the metal edge of the End Plate into the Slots in Reciever Extension Nut with a Center Punch.)


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## bigdaddyflo (Jul 27, 2012)

*Detent spring mod*

If you are finished with your build, then this won't help you, but if you have not installed your end plate and castle nut, here is a simple mod to help with the takedown detent spring. This helps with assembly of the end plate and castle nut since the spring and detent are installed using this mod. 
This is not my video...






I personally don't use loc-tite on this mod.


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## THE JAMMER (Aug 1, 2005)

thanks guys. I don't want to look like a buffoon, but I have read in multiple places, Cheaperthandirt's video being one of them, that said 40 inch pounds- not 40 ft pounds. In doing further research after I posted this post, it certainly seems that it is ft pounds.

Thanks.


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## THE JAMMER (Aug 1, 2005)

bigdaddyflo said:


> If you are finished with your build, then this won't help you, but if you have not installed your end plate and castle nut, here is a simple mod to help with the takedown detent spring. This helps with assembly of the end plate and castle nut since the spring and detent are installed using this mod.
> This is not my video...
> 
> 
> ...


Biddaddyflo I watched that video. Very cool mod. Looks like a bit of a pain pushing the screw in on top of the spring to initially get it started, but after that most of us will probably never ever take that out again. Whereas changing buffer tubes, might be done more often.


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## muney pit (Mar 24, 2014)

Never used a torque wrench on a ar.


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## Jungle_Jim (Nov 16, 2007)

Just tighten the hell out of it with your wrench and stake it in 3 places.


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## Pocketfisherman (May 30, 2005)

THE JAMMER said:


> Jut finished my first ar lower build, and have a quesion. Where the heck do you find a torque wrench that measures in inch pounds to torque down the castle nut on the buffer tube, and eventually a barrel on an upper build.


Bought mine at Sears. They had about 4 different sizes with the smallest doing inch pounds and newton meters. It's essential for bolts screwed into Aluminum like you find on a Harley.


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## bigdaddyflo (Jul 27, 2012)

THE JAMMER said:


> Biddaddyflo I watched that video. Very cool mod. Looks like a bit of a pain pushing the screw in on top of the spring to initially get it started, but after that most of us will probably never ever take that out again. Whereas changing buffer tubes, might be done more often.


I didn't think I would take one apart either, but I have had three taken apart this year. I changed end plates on two rifles to single point attachments - it was so nice not dealing with the detent spring. And on another rifle, I had to remove the single point sling end plate and put on a regular end plate to use my Christmas gift (bump stock) my Marine son bought me!


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## THE JAMMER (Aug 1, 2005)

OK, I just watched brownell's video and read their notes, and both said inch pounds not foot pounds. ***???


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## bigdaddyflo (Jul 27, 2012)

THE JAMMER said:


> OK, I just watched brownell's video and read their notes, and both said inch pounds not foot pounds. ***???


The setting should be 40 foot pounds (+\-2 ft.lbs.). Not 40 inch pounds.


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## dwilliams35 (Oct 8, 2006)

I've used one on a barrel nut once, never bothered on the castle nut...


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## THE JAMMER (Aug 1, 2005)

bigdaddyflo said:


> The setting should be 40 foot pounds (+\-2 ft.lbs.). Not 40 inch pounds.


So brownell's video is wrong??


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## BradV (Jun 27, 2012)

It is definitely foot pounds. 40 inch pounds would be 3.33 foot pounds, hardly even hand tight. 

Tighten it up and stake it. You won't have any trouble.


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## bigdaddyflo (Jul 27, 2012)

THE JAMMER said:


> So brownell's video is wrong??


Here's the Brownells video...3:08 is where he says 38-42 foot pounds...
http://www.brownells.com/.aspx/lid=10364/GunTechdetail/Changing-Standard-Butt-Stock-To-Collapsible

Yes, it is definitely in foot pounds. If you want to do 40 inch pounds, I think you will have your buffer tube and stock "wobbling" around after a few shots. I have personally built 9 lowers. And this is my next build - another 300 Blackout.
Good luck!


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## THE JAMMER (Aug 1, 2005)

bigdaddyflo said:


> Here's the Brownells video...3:08 is where he says 38-42 foot pounds...
> http://www.brownells.com/.aspx/lid=10364/GunTechdetail/Changing-Standard-Butt-Stock-To-Collapsible
> 
> Yes, it is definitely in foot pounds. If you want to do 40 inch pounds, I think you will have your buffer tube and stock "wobbling" around after a few shots. I have personally built 9 lowers. And this is my next build - another 300 Blackout.
> Good luck!


Bigdaddyflo, Here is the other brownells video that I watched indicating inch pounds. Not trying to beat a dead horse. I think it is pretty obvious that it is foot pounds. Just a shame that a major company like brownells would have something like this out there.

www.brownells.com/.aspx/lid=11642/learn/


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## bigdaddyflo (Jul 27, 2012)

THE JAMMER said:


> Bigdaddyflo, Here is the other brownells video that I watched indicating inch pounds. Not trying to beat a dead horse. I think it is pretty obvious that it is foot pounds. Just a shame that a major company like brownells would have something like this out there.
> 
> www.brownells.com/.aspx/lid=11642/learn/


I see that! h: I have sent an email to their "Gun Tech" to see what they have to say on their video! I will get back to you with their response!


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## bigdaddyflo (Jul 27, 2012)

This is the response from Brownells...


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## bigdaddyflo (Jul 27, 2012)

And here was my question...


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## THE JAMMER (Aug 1, 2005)

BUDDA BING BUDDA BOOM. They didn't seem to be too concerned about their error did they.


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## bigdaddyflo (Jul 27, 2012)

THE JAMMER said:


> BUDDA BING BUDDA BOOM. They didn't seem to be too concerned about their error did they.


No, they didn't seemed too concerned of their error and how people do rely on their "expertise". In fact I responded back to their email to see if they were going to correct the video. I have not received a response for that question.

Good luck on your build - post a picture when you finish it!


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