Gas Key Rubs Gas Tube

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[ARCHIVED THREAD] - Gas Key Rubs Gas Tube

Posted: 1/16/2021 12:49:59 AM EDT

At what point would some consider it excessive? The rifle fires and functions, but I notice that the gas key seems to very slightly rub or maybe barely gets hung up on the gas tube.

I remember reading on here one time a few years ago about someone having the same issue. Someone in that thread mentioned a tool that could be used to gently bend the gas tube. Does anyone know if such a tool still exists? Also, on that note, what would be the best way to tell which direction the gas tube should be adjusted?

Posted: 1/16/2021 1:26:49 AM EDT

[#1]

Quoted:
At what point would some consider it excessive? The rifle fires and functions, but I notice that the gas key seems to very slightly rub or maybe barely gets hung up on the gas tube.

I remember reading on here one time a few years ago about someone having the same issue. Someone in that thread mentioned a tool that could be used to gently bend the gas tube. Does anyone know if such a tool still exists? Also, on that note, what would be the best way to tell which direction the gas tube should be adjusted?

View Quote

flat blade screwdriver

Posted: 1/16/2021 1:34:16 AM EDT

[#2]

Quoted:
At what point would some consider it excessive? The rifle fires and functions, but I notice that the gas key seems to very slightly rub or maybe barely gets hung up on the gas tube.

I remember reading on here one time a few years ago about someone having the same issue. Someone in that thread mentioned a tool that could be used to gently bend the gas tube. Does anyone know if such a tool still exists? Also, on that note, what would be the best way to tell which direction the gas tube should be adjusted?

View Quote

A large 1/4 inch or so flat bladed screwdrivers works...

Lazy man's technique.

Remove the bolt from the carrier. And place the carrier in the raceway.
Do not remove the CH.

Twist the inserted carrier slightly clockwise. And slowly feel for resistance.
And do the same counterclockwise. It should feel identical.

If not, whichever side has a rub, has to be "bent" toward center.

You can also remove the tube and place it's end, in tightly set crescent wrench jaws.
And bent it.

I find the first method more effective. Because it is immediate, if you have it or not.

Insert the blade of the screwdriver in the tight side, between the gas tube and CH.
You use some pressure, and turn the blade so the contact is toward the end of the gas tube.

Posted: 1/16/2021 1:44:33 AM EDT

[#3]

Okay that makes sense. I’m absolutely looking for the lazy man’s way as I could disassemble and adjust but this is an adjustment id rather not overdo and crimp the tube so I want to avoid taking it apart and putting it back together many times.

Thank you for your help. I’ll give it a shot tomorrow and see what happens.

Edit: How big of a potential issue is this in respect to reliability?

Posted: 1/16/2021 1:51:51 AM EDT

[#4]

You wont over do it. It is kinda hard to bend.

The contact can also be up and down.
You can use an allen wrench for down. You remove the CH for this one.

Up can be done with a hammer and punch. The punch is placed just past the bulb end of the gas tube.
This one has to be done carefully. You can ham hand it, and garf the tube.

Posted: 1/16/2021 2:24:28 AM EDT

[#5]

Thank you for the explanation. This is a build I put together a while ago and didn’t want to shoot it anymore til I figured it out.

Each build seems to be an adventure lol

Posted: 1/16/2021 8:00:50 AM EDT

[#6]

Don't bend the end of the gas key from withing the inside of the receiver, it will just cause more problems.

Start off my removing the hand guards, so you can get a good look at the gas tube through the delta or tube nut channel, to make sure that the tube/Barrel nut has been installed with it's tube passage aligned to the upper receiver gas block, to confirm that that gas tube is free floating through the two/not begin bound up against the two channels mis-indexed together.

Now if gas tube is free floating in the two channels aligned together, pull the bolt off the carrier and using just the carrier with key in the upper, check the alignment of the tube to carrier key. If the gas tube does need to be tweaked to align the end of tube to carrier key, then tweak the tube over the center of the barrel.

Again, do not try to tweak the end of the tube where it comes out into the upper receiver B/C void with a tuol back there, or loosen a gas block to try to rotate it on the barrel.

Simply, but trying to tweak just the end of the tube, may get the gas tube to initial entering the key correctly, but can end up with the tube kinked off axis where it goes through the barrel nut and upper channel, to have the gas tube binding in the channel as the bolt locks up instead. So by tweaking the tube over the barrel in the middle of the gas tube, keeps the end of the gas tube through the barrel nut/upper tube channel/out the back side straight/fully inline with the carrier key channel for it full travel over the tube.

Posted: 1/16/2021 12:18:04 PM EDT

[#7]

Not for the poors.........

http://www.m-guns.com/tools.php click on gas tube bender. These are mostly for people that love and collect gun specific tools.

Posted: 1/16/2021 1:47:45 PM EDT

[#8]

Quote History

Quoted:
Don't bend the end of the gas key from withing the inside of the receiver, it will just cause more problems.

Start off my removing the hand guards, so you can get a good look at the gas tube through the delta or tube nut channel, to make sure that the tube/Barrel nut has been installed with it's tube passage aligned to the upper receiver gas block, to confirm that that gas tube is free floating through the two/not begin bound up against the two channels mis-indexed together.

Now if gas tube is free floating in the two channels aligned together, pull the bolt off the carrier and using just the carrier with key in the upper, check the alignment of the tube to carrier key. If the gas tube does need to be tweaked to align the end of tube to carrier key, then tweak the tube over the center of the barrel.

Again, do not try to tweak the end of the tube where it comes out into the upper receiver B/C void with a tuol back there, or loosen a gas block to try to rotate it on the barrel.

Simply, but trying to tweak just the end of the tube, may get the gas tube to initial entering the key correctly, but can end up with the tube kinked off axis where it goes through the barrel nut and upper channel, to have the gas tube binding in the channel as the bolt locks up instead. So by tweaking the tube over the barrel in the middle of the gas tube, keeps the end of the gas tube through the barrel nut/upper tube channel/out the back side straight/fully inline with the carrier key channel for it full travel over the tube.

View Quote

Was trying to avoid taking the hand guard off, but I don’t think I used any thread locker on it. I think it’s an UnbrandedAR freefloat hand guard.

Anyways, the barrel is a ballistic advantage mid length that came with the gas block cross drilled to pin to the barrel, so my adjustments as far as the gas block goes are limited.

I don’t think that would be the issue, anyways because I trust their machining. I’ve seen a new gas tube slightly bent before, but I wouldn’t think that the case either. i might have to see about replacing the gas tube if I can tell it’s bent.

Posted: 1/16/2021 1:49:52 PM EDT

[#9]

Quote History

Quoted:
Not for the poors.........

http://www.m-guns.com/tools.php click on gas tube bender. These are mostly for people that love and collect gun specific tools.

View Quote

Thank you, OTDR. That’s the tool I remember seeing. I’m not seeing a way to order though

Posted: 1/16/2021 4:39:09 PM EDT

[#10]

Quote History

Quoted:

Thank you, OTDR. That’s the tool I remember seeing. I’m not seeing a way to order though

View Quote

That guy who runs that site not very interwebs savy. You have to look at the price, add shipping and then send funds via paypal and explain in the paypal notes what your ordering and make sure your name, address and everything matches so he can understand it. Its not a good sight for easy ordering. There is no traditional cart. I have ordered many tools from him, never any issues.

That being said, Ned is a highly respected professional in the firearms community, he writes tech columns for AR-15 magazine, makes great tools, just his website sux.

Posted: 1/23/2021 9:04:14 AM EDT

[#11]

https://www.brownells.com/gunsmith-tools-supplies/rifle-tools/wrenches/ar-15-m16-308-ar-gas-tube-wrench-prod25017.aspx

FWIW... a poor gas tube to gas key interface can easily cause inconsistent accuracy.

You really "want" smooth action between the 2.

https://www.thefreelibrary.com/Gas+Tube+Alignment%2c+Revisited%3a+The+never-ending+saga+continues....-a0540679188

Posted: 2/8/2021 12:09:24 AM EDT

[#12]

Quote History

Quoted:
https://www.brownells.com/gunsmith-tools-supplies/rifle-tools/wrenches/ar-15-m16-308-ar-gas-tube-wrench-prod25017.aspx

FWIW... a poor gas tube to gas key interface can easily cause inconsistent accuracy.

You really "want" smooth action between the 2.

https://www.thefreelibrary.com/Gas+Tube+Alignment%2c+Revisited%3a+The+never-ending+saga+continues....-a0540679188

View Quote

i never thought of that. the interference can introduce unwanted harmonics. thanks for that.

i tried to get in there to bend it but theres not enough room with it assembled. it needs to be bent slightly towards the ejection port from what i can tell.

this isnt my go to rifle so im not too worried about getting it fixed right away, just checking my options.

thank you everyone for your time and thoughts!

Posted: 2/8/2021 1:01:12 PM EDT

[#13]

Quote History

Quoted:

i tried to get in there to bend it but theres not enough room with it assembled. it needs to be bent slightly towards the ejection port from what i can tell.

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Large flat blade screwdriver.

Posted: 2/9/2021 4:15:28 AM EDT

[#14]

Again, do not bend the tube from within the receiver. You do this to kink the end of the tube, which will pull the end of the tube off axis of the key line, you may get the end of the tube to enter the key to start with, but since the tube is now kinked from say the end off the upper receiver tube channel back, when the B/C is all the way forward, the key will be binding on the tube channel side at that start point of the kink instead.

Pull the hand guard, and bend the tube at the center of it above the barrel to align the end of tube with the key. This will keep the entire tube end through the barrel nut and upper receiver tube channel straight/ in line with the carrier key channel axis, for a clean index with the key channel axis for the entire engagement through bolt lock up.

Posted: 2/9/2021 3:48:01 PM EDT

[#15]

Quote History

Quoted:
Again, do not bend the tube from within the receiver. You do this to kink the end of the tube, which will pull the end of the tube off axis of the key line, you may get the end of the tube to enter the key to start with, but since the tube is now kinked from say the end off the upper receiver tube channel back, when the B/C is all the way forward, the key will be binding on the tube channel side at that start point of the kink instead.

Pull the hand guard, and bend the tube at the center of it above the barrel to align the end of tube with the key. This will keep the entire tube end through the barrel nut and upper receiver tube channel straight/ in line with the carrier key channel axis, for a clean index with the key channel axis for the entire engagement through bolt lock up.

View Quote

Not wanting to pull the handguard is just silly. Dano523 is giving you good advice here. Straighten the gas tube alignment from the source, that means the gas block and barrel nut locations.

Check the barrel nut first, if the gas tube is contacting the barrel nut it's being tensioned as it enters the upper receiver. That needs to be addressed first. Once you have the barrel nut tightened without contacting the gas tube then you can rotate the gas block slightly if you still have an issue. Double check the barrel nut again after moving the gas block.

This may seem tedious, but your rifle will be more accurate (within the limitations of the barrel and ammo quality) and you won't be creating abnormal wear on any parts.