Building AR by clamping barrel

AB_blaster said:
There is no torque on the index pin with the reaction rod just on the extension itself.
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The barrel nut tightens to the threads in the reciever...
If you arent holding the upper reciever you are torquing thru the index pin, no exceptions

While it works to tighten thru the index pin, a better way is to use a upper reciever vice... If you are planning on going full gorrilla use the upper reciever vise with the bcg installed. If you flex the reciever enough and it tightens on the bcg it will still flex back good as new... That is if you must overtorque it
 
Whats the torque value on a barrel nut?

2strokeforever: the way you are saying it event the old school way with barrel blocks would put pressure on the pin.
 
TrxR said:
Whats the torque value on a barrel nut?

2strokeforever: the way you are saying it event the old school way with barrel blocks would put pressure on the pin.
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30 ft lb to 80 ft lb MAX, but seriously about 32 to 34 is good.

The best way to torque a barrel nut is to clamp down on the receiver because the barrel nut goes on the receiver. The best way to torque a muzzle device is to clamp on the barrel itself ( NOT the barrel extension ) - theoretically.

Bev block or reaction rod become popular because people start making non-standard receiver. Many free floating hand guards also interfere with the typical upper receiver clamping block.

Now think of it as a "work flow" problem. The"army" way of clamping the barrel is the most practical / time efficient to do work on rifles without free floating hand guard. But with free floating hand guard and non standard receiver, reaction rod is much faster. The more you have to change tools and re-set up, the slower the entire process.

In simple words, you can clamp on the barrel, upper or use the reaction rod. They all work within the torque values required.
 
This is straight from ARMY TM9-1005-319-23&P

Apply Moly Disufilde grease to thread. 30 ft-lb, do it three times.

Sometimes the gas tube is not aligned but it can't be under torqued, so realistically 32 to 34 is perfect when the gas tube is aligned.
 
The reason for the huge gap in torque specification of 30ft/lbs to 80 ft/lbs is because of the original barrel nut design, if you haven't achieved the minimum of 30 ft/lbs when the gas tube cutout of the barrel nut aligns with the gas tube hole in the receiver ot you got slightly past it when you get to 30ft/lbs, you gotta torque to the next gas tube cutout.

Also, copper-based anti-seize as been used VERY extensively by american armorers (both military and civilian tactical shops) on barrel nuts, with no ill effect through the life cycle of the barrel, that is, when the barrel becomes shot out and it's time to replace it the barrel nut has not seized nor galled on the receiver. Even if the Loctite C5A copper anti-seize (what they mostly use) and Permatex copper anti-seize componds contain a small amount of graphite in the mix, it doesn't cause a problem. It's designed to prevent galling and seizing, so it doesn't.

You can use the proper moly grease if you want, but you have to be aware that anti-seize has been used successfully.

Not all moly greases are created equal, most of the stuff you'll find around is graphite based, you don't want that.

Also, it's a very good idea to apply metallic anti-seize on the muzzle threads.
 
Lots of good info on here. Thankyou for that! It’s much appreciated. Perhaps I will reach out to borrow/rent a proper tool for my SLR but the AR seems to be set up just fine using the vice method.
 
Well, well, isn't this a timely thread, I have a new to me Upper in the mail. So a little moly grease, torque wrench, combo tool, and my hardwood barrel blocks are all I need, Outstanding!!!

Since we're on the topic, What punches do I need to remove my fixed front sight (HBAR), and can I reuse the pins?
 
I use a brass punch not to marr and mushroom the pins when they're taper pins, when they're straight pins I use a steel punch that is ever so slightly smaller than the pins. You can reuse the pins.
 
For fsb i use a 3/8" steel taper punch to break the taper pins loose, then a 1/8" steel taper punch to push them through. Brass is less than ideal
 
*MALICE* said:
For fsb i use a 3/8" steel taper punch to break the taper pins loose, then a 1/8" steel taper punch to push them through. Brass is less than ideal
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We met last year at one of Barney's matches (PR3), I was his lackey/Chalkriver's spotter on match day.

I can see why he'd use a Brass Punch, I guess if the pins were stubborn all you'd achieve is trashing your punch though.

I was going to use a street hockey puck as a bench block, do you think it's too soft for the job?

Can anyone comment on the quality of the NCStar Combo tools? Checked mine (other brand) last night and the hole for my torque wrench is a little sloppy.
 
redshooter said:
Can anyone comment on the quality of the NCStar Combo tools? Checked mine (other brand) last night and the hole for my torque wrench is a little sloppy.
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I destroyed 2...the new versions with pins. They flex...teeth come out slightly and gets sheared off. Get the usgi version if you can find one...then use a breaker bar to unscrew.
 
I've read only good things about the Magpul wrench.

EDIT: yeah... they're expensive alright lol.
 
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shhh said:
I most strongly disagree.
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Dietz said:
That is some top level disinformation right there.

You change "a lot of barrels" this way? Holy ####.
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Woops I was wrong, I meant to say to use moly grease around the barrel extension to slip it into the receiver and also the upper receiver's threads for the barrel nut to torque over. I was thinking of another rifle when typing that which doesn't require any kind of lube which I just worked on.

As for copper anti-seize, look up galvanic corrosion like Uisge mentioned. We use it for steel on steel but never for aluminum.
 
This is only an issue if the anodizing of the receiver threads is damaged and the barrel nut is repeatedly exposed to sal####er, and moly grease will not prevent it either because it burns off during use. Many Colt barrels have fallen off receivers of navy guns in the past.

Use moly if you're afraid. I can see how someone living on the coast might run into an issue because of the salt in the air.

Either way, TrurNorthArms sells 1/8oz AeroShell 64 for 5.97, or you can buy a 14oz tube of AeroShell 64 for 26.50$ from a Canadian AeroShell retailer.

https://truenortharms.com/products/aeroshell-33ms-lithium-moly-synthetic-grease?variant=25717902984
 
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redshooter said:
We met last year at one of Barney's matches (PR3), I was his lackey/Chalkriver's spotter on match day.

I can see why he'd use a Brass Punch, I guess if the pins were stubborn all you'd achieve is trashing your punch though.

I was going to use a street hockey puck as a bench block, do you think it's too soft for the job?

Can anyone comment on the quality of the NCStar Combo tools? Checked mine (other brand) last night and the hole for my torque wrench is a little sloppy.
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I've heard of people using them.....but I've never heard of people having good results? lol

I open the jaws on a standard bench vise just enough to support both sides of the fsb, then I have a lovely assistant hold the upper in position while I hit the pins with a big hammer and a 3/8 solid steel taper punch. Once the taper pins 'break loose' (ie. the head is now flush with the fsb), I use the 1/8" steel taper punch to tap them through. Using brass punches is only going to result in chewed up brass punches. I have used this method on all taper pins, even the 'dreaded' norinco ones.....and they all came loose with a couple whacks. The trick is to have the fsb resting on something solid that CANNOT give when you hit it. The carpet on a basement floor or ones lap are not the ideal surfaces to attempt this ;)

You can reuse the pins with the same barrel/fsb, assuming they weren't completely mangled when you punched them out. But I've never had the problem to date......
 
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Clamping the barrel is the old way and works just fine but I prefer the reaction rod as I can position it in the vise in any orientation and there is no chance of over-tightening the vise on the barrel and there is no chance of it slipping or marking the barrel.
Clamping the upper receiver in a vise in the clam-shell blocks is not a good way to tighten the barrel nut, that is a lot of force being transferred into the upper receiver through very little material where the threads meet the receiver. It will work but you are risking damage to your receiver.
I've always put the barrel nut on dry and have never had any problems with corrosion or seizing of the nut. I recently picked up some moly though so may try lubing my next build to see if it's any better.
 
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cr5 said:
Clamping the barrel is the old way and works just fine but I prefer the reaction rod as I can position it in the vise in any orientation and there is no chance of over-tightening the vise on the barrel and there is no chance of it slipping or marking the barrel.
Clamping the upper receiver in a vise in the clam-shell blocks is not a good way to tighten the barrel nut, that is a lot of force being transferred into the upper receiver through very little material where the threads meet the receiver. It will work but you are risking damage to your receiver.
I've always put the barrel nut on dry and have never had any problems with corrosion or seizing of the nut. I recently picked up some moly though so may try lubing my next build to see if it's any better.
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If you were able to crush a barrel by clamping it in a barrel vise........man, I'd be afraid to shake your hand ;)
 
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