You can open your bench vise and hold the gas tube in the vise.  Use a wood block and hammer and tap the end of the upper receiver forward (same direction as bullet out of bore) to help loosen the gas tube.

Gravity can also work for you if you point the barrel down while holding gas tube in vise.  Tap the upper receiver.

If you need pics of what I'm talking about, let me know.

[b][red]GOT IT![/b][/red]    I sprayed penetrating oil into where the gas tube enters the gas block, then let that sit awhile. Degreased the tube with some alcohol and then wiped it dry.  I then used a piece of rubber inner-tube to pad the pliers, gripped the tube with them, and hit the pliers several times with a small hammer- finally got it out!  No damage done to the tube either.  

Thanks for the advice, fellas.  Now I wish I would have bought a new gas tube to go along with my new bbl so I could keep the old one as a spare.  

EDITED TO ADD: Got the bbl removed this morning as well, now I'm waiting for UPS  to bring the new bbl today.

WOW..

Did that ever answer some nagging questions.  There I was delaying ordering a barrl for my 10 year old son's M4gery project.

Not any more!

What if i want to put a float tube on it?

thank you

Quoted: What if i want to put a float tube on it?

I have been meaning to do a float tube install step by step... justy havent had time.

To install a float tube, is basically the same, except you have to remove the front sight base if so equipped.  Float tubes either thread directly on the receiver, or come with a special barrel nut that the tube threads on to.  It's going to be tought to design a step by step for all the models out there.

OK.  thanks.  my next project is to build two uppers, and I want them floated.  
Makes, I don't know yet, but I'm looking to do 16" with at least a partial float.

OK, I went to my local hardware store yesterday and asked about this moly/dis grease so they pointed to the isle and said you can find it their, not. What are the properties of this grease that make it required for  barrel assembly? I have in front of me a can of LubriMatic high temp brake drum grease, is that the same? If not the search continuies, so far this has been the most hardest part to find.

I wonder if "Never Sieze" would work?!?

$bob$

It's usually really easy to find in any hardware store, or auto parts store.

It's called "anti-seize" compound, and comes in copper based and aluminum based.  I like the aluminum based stuff.

Typically comes in small single use packets, a small tube, or in a can with a brush attached to the lid.

I finally replaced my worn A1 upper with a brand new A3, and I'm surprised how easy the whole thing went together.  The hardest part was getting the roll pin out of the gas tube.

Tack, Tack, Tack.  Maybe that will hold this thread till I get my new barrel.  

Quoted: OK, I went to my local hardware store yesterday and asked about this moly/dis grease so they pointed to the isle and said you can find it their, not. What are the properties of this grease that make it required for  barrel assembly? I have in front of me a can of LubriMatic high temp brake drum grease, is that the same? If not the search continuies, so far this has been the most hardest part to find.

I believe the stuff you find in the hardware store might contain something that reacts unfavorably with aluminum.  I don't remember what exactly, hopefully someone else will be along with the complete details .

Quoted: [I believe the stuff you find in the hardware store might contain something that reacts unfavorably with aluminum.  I don't remember what exactly, hopefully someone else will be along with the complete details .

I have used moly from various car stores without a problem for years...

mark
[email protected]

Hi guys,

How about DCM Freefloat tubes?  This thread has motivated me to build a custom AR which will also be my first.  I was previously intimated by barrel installation but no more. hat
Paul

Just assembled a upper following the directions. It all went together with out a problem. Great directions!

Never Seize and other metal particle containing antisieze materials (aluminum or copper) are initended for use with steel on steel.  When you use this on an steel to aluminum, the metal particles get embedded in the soft aluminum threads.   Don't use Never Seize.

OK, let me 'spain it to you like this... Never Seize is not for every lubricating purpose (and not for this one).  It is fine for use on head studs on an engine block, but you would not put it on the mains and rod bearing for assembly lube, would you?  You would not pack wheel bearings with it, would you?  Well, I am telling you, it is not the product to use on the barrel nut.

Moly grease is ordinary wheel bearing grease, nothing more.  If you don't have this, grease from your grease gun is just fine.  It is not a big deal.  We just want to use a good grease that will support high pressures and still slip.

The purpose of the grease is not so that you can later remove it.  The purpose is so that you can smootly tighten up the nut without galling the threads right now during this install.  

As far as "proper torquing", you need it tight enough to not loosen, which is as low as 25 ft-lb.  If you get alignment at 27, leave it alone.  If you want to go "by the book" torque it to 30, then don't look at the wrench again.  The 30 is a recommended minimum, nothing more.  There is NO WAY the rifle could be manufactured such that, for example 45 ft-lb was "correct" and the notch would automatically line up at 45.  There is no "correct" figure.  Whatever it takes over 30 ft-lb (I will go so far as to say over 25) to achieve alignment is correct.

Once the nut is "tight" (minimum), going further to achieve alignment what you are really doing is distorting the softer aluminum threads, pulling the aluminum toward the front of the receiver.  This is necessarry to get the nut to rotate enough to align.  (And this is why you don't want a steel upper)  Hopefully, this should happen within a half notch of rotation and the threads will not be stripped.  And they won't unless there is a serious problem.  Due to the stresses, some lubrication, the grease, is needed to do this smoothly and not damage the rifle.

OK, the barrel is installed, nut tight, aligned.  After years of shooting, 30-40,000 rounds, the barrel is finally worn out.  Well, in my opinion, so is the upper receiver, toss both.  

IF you want to change barrels for another reason, to go from A2 to flattop for example, fine, but the more a barrel is changed on one upper, the more stress put on the threads of that upper.  Barrel install should really be a one time thing for a given upper, or no more than a few times.

Really appreciate all th help and information on thi site. I installed a bushy 16 in. barrel on my colt upper with no trouble, thanks to the info here. Thanks for all the help!!

Hi can anyone tell me the size of the thred on the receiver(for the barrel nutt).

The anti seize stuff they use on spark plugs should work--that's steel on aluminum in many cases, and plenty hot too.

Guys, thanks for making this a sticky.  I am planning to put a FH on my post ban barrel and just realized that it being a bull barrel that I will have to either change barrels or get mine turned down prior to threading.  Which ever way I go will depend on price.  A new barrel may be cheaper than paying a machinist to turn it.  Either way, since you guys have generously shared you infinite wisdom, I should have no trouble yanking my barrel and installing one more much needed evil feature just because I can.  Thanks again!

I just followed the instructions to install my new threaded barrel. Nary a hithch.

Thanks for the info!

^

Quick question....I finally have decided to build my own upper. This thread has been a great help, thanks Falark and everyone else who contributed.
About moly grease...the Bushmaster armorers video shows their upper being put together with just motor oil. I went out yesterday and bought a big ole can of grease and I intend to use it. Does the use of moly grease come from the military? I did 8 years as an infantryman in the army but never hung with the armorers (wish I had now, damn this black rifle disease ). And is the grease used for it's anti-seize properties?

Thanks to all of you for your knowledge.  

tag

Don't use the silver, gold or any color anti seeze, It's purpose is not to lubricate but to make sure things don't rust and rot together so you can get it apart again. It's main use is automotive and marine. I'm sure some have used it and have had no trouble but eventually it's going to cost an upper.  Moly is meant as a lubricant and will suit this purpose very well.
As for a stuck gas tube, we have that problem with certain cars and the distributor or oil pump drive shaft, We use carb cleaner to break loose the carbon and varnish that build up. It takes about a min or so to soak in and even the most stubborn parts will free up and come apart :) with little effort.

Greg

Thanks, FAL!!  I've got some barrel changing to do!

Tag and BTT

Thanks for the info

Echap

FALARAK  

Great post, thanks for the excellent pictures.  I have a few questions.  This is my first time attempting to do something this major with my rifle and I want to do it right the first time.

1. I have the -23 manual, the barrel tool, a vise, and soon will have the receiver blocks.  My rife is a "post-ban" Bushy A2 carbine.  I want to take the barrel off to turn and thread the muzzle and then replace.

2. I do not have the moly grease and have not located any yet in my area.  Everything here seems to be a lithium based grease (automotive type).  Will this work or should I look harder?

3. The barrel tool I have has the three pins on one side and on the other side is a "wave" type pattern.  Which is the proper one to use to remove the barrel nut.  I have taken the handguards off and the "wave" side looks like it will fit.

Any suggestions and help are welcome.  

Quoted: 2. I do not have the moly grease and have not located any yet in my area.  Everything here seems to be a lithium based grease (automotive type).  Will this work or should I look harder?

Mail order.  Links are provided.  If not, then it is accepted that other greases will "work" but are not optimal.  You pretty much want a hi temp, no graphite grease.  Look to wheel bearing grease and the like.

3. The barrel tool I have has the three pins on one side and on the other side is a "wave" type pattern.  Which is the proper one to use to remove the barrel nut.  I have taken the handguards off and the "wave" side looks like it will fit.

"Wave" side is for the standard barrel nut.

Good thread! I have a question, my rear site is cranked pretty far to the left to get it zeroed. It looks like I could remove the barrel and just reinstall straighter?

Quoted: "Wave" side is for the standard barrel nut.

As opposed to....?

Sarge

tagged

tag

Quoted: Quoted: "Wave" side is for the standard barrel nut. As opposed to....? Sarge

perhaps the rear sights are not tight in the varry handle and are pitched counter clockwise?

try tightening the screw from below after opening up the reciever and removing the bc

Quoted: Good thread! I have a question, my rear site is cranked pretty far to the left to get it zeroed. It looks like I could remove the barrel and just reinstall straighter?

This is common.  It's been covered in here before... but I cant find where I described the process.....  You need to file open the right side of the upper receiver just a tad, where the barrel extension pin is located in the receiver slot.  Then, using a center punch, stake the left side of the receiver slot, ever close to the edge, to "swell" the receiver in that location, just to the left of the barrel extension pin.  This will *rotate* the barrel to the right, then torque the barrel back on.  It takes a little playing, but using this method, you can get it centers perfectly.  It really helps to use a laser boresighter in theis process.  Unless your rear sight is all the way to one side, it probably is not worth it....  However, if you are comfortable with the process, you can get it smack dab centered, which is a great feeling!

Quoted: -------------------------------------------------------------------------------- Quoted: "Wave" side is for the standard barrel nut. -------------------------------------------------------------------------------- As opposed to....? Sarge

As opposed to the other side of the armorer's tool/barrel wrench, with the three pins, which is used for free float tubes.

Falarak,

Thank you for your instructions.  I just put together my first rifle, well still waiting on the barrel, but everything is ready.  Printed your instructions, took about an hour.  Once again THANKS.

Dear Falarak,
I want to thank you for this reference. You have made this completely idiot proof & a real joy to work on AR-15's.

.

Quoted: Quoted: Good thread! I have a question, my rear site is cranked pretty far to the left to get it zeroed. It looks like I could remove the barrel and just reinstall straighter? This is common.  It's been covered in here before... but I cant find where I described the process.....  You need to file open the right side of the upper receiver just a tad, where the barrel extension pin is located in the receiver slot.  Then, using a center punch, stake the left side of the receiver slot, ever close to the edge, to "swell" the receiver in that location, just to the left of the barrel extension pin.  This will *rotate* the barrel to the right, then torque the barrel back on.  It takes a little playing, but using this method, you can get it centers perfectly.  It really helps to use a laser boresighter in theis process.  Unless your rear sight is all the way to one side, it probably is not worth it....  However, if you are comfortable with the process, you can get it smack dab centered, which is a great feeling!

I have this problem big time. Even after shoving windage all the way to the left, my shots are still hitting far right. Just ordered the vice and tools to fiddle with the barrel.

so after getting something to nudge the rear of the barrel right (so that its aligned properly), I should begin tightening the barrel nut? Would that hold the barrel in place in its new corrected position?

Quoted: so after getting something to nudge the rear of the barrel right (so that its aligned properly), I should begin tightening the barrel nut? Would that hold the barrel in place in its new corrected position?

He said:

Quoted: Then, using a center punch, stake the left side of the receiver slot, ever close to the edge, to "swell" the receiver in that location, just to the left of the barrel extension pin.  This will *rotate* the barrel to the right, then torque the barrel back on.

Hey FAL, thanks for all this help with the building process, One quick question, after removing the gas tube from the FSB, I plan on removing the FSB itself following your post instructions, how do you remove the handguard cap from the FSB? Is it pinned to it or should I just slide it off the barrell after the FSB is gone? I have never done anything like this and wanted to get all the doubts off my mind before trying.

Thanks

Quoted: I plan on removing the FSB itself following your post instructions, how do you remove the handguard cap from the FSB? Is it pinned to it or should I just slide it off the barrell after the FSB is gone?

It just falls off the barrel when the FSB is removed.