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Old September 15th, 2018, 11:07 PM #11
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Originally Posted by 3paul10 View Post
I love mysteries.....do you have a carbine, midlegth or rifle gas tube?
Carbine. I'm just wondering if that little bit of the gas tube surface exposed will catch the gas coming out of the barrel gas port when firing and end up causing a gap to form and just blowing gas out the back of it.
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Old September 16th, 2018, 08:20 AM #12
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Originally Posted by pidevildog07 View Post
Carbine. I'm just wondering if that little bit of the gas tube surface exposed will catch the gas coming out of the barrel gas port when firing and end up causing a gap to form and just blowing gas out the back of it.
I don't think that will be a problem either. Put it together and fire it before you buy a new gb.
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Old September 16th, 2018, 09:38 AM #13
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Originally Posted by pidevildog07 View Post
Carbine. I'm just wondering if that little bit of the gas tube surface exposed will catch the gas coming out of the barrel gas port when firing and end up causing a gap to form and just blowing gas out the back of it.


I wouldn't worry about that. Gas blocks self seal via fouling. Let that happen and don't remove the GB to 'clean' the fouling. All GBs do this as part of the break-in process.
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Old September 16th, 2018, 02:11 PM #14
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Originally Posted by outrider58 View Post
[/B]

I wouldn't worry about that. Gas blocks self seal via fouling. Let that happen and don't remove the GB to 'clean' the fouling. All GBs do this as part of the break-in process.
I'll tell you this, with the gas tube/block assembly pinned together detached from the barrel, I covered the gas tube/block hole with my finger and blew into the receiver end of the tube and could hear and feel air escaping from the area where the tube slides into the block.

I don't want to sound like I'm calling you a liar, your post count tells me you're well versed in firearms in general. I'm just having a hard time believing that carbon fouling is going to hold back a force of 45k+ psi.
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Old September 16th, 2018, 03:16 PM #15
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Originally Posted by pidevildog07 View Post
I'll tell you this, with the gas tube/block assembly pinned together detached from the barrel, I covered the gas tube/block hole with my finger and blew into the receiver end of the tube and could hear and feel air escaping from the area where the tube slides into the block.

I don't want to sound like I'm calling you a liar, your post count tells me you're well versed in firearms in general. I'm just having a hard time believing that carbon fouling is going to hold back a force of 45k+ psi.
Outrider is correct.

Carbon is like clotted blood. The gas system will bleed carbon till it seals up.

Some people insist on cleaning the barrel after each time it's shot. This works against the carbon clotting and tries to unclot the carbon.

It is possible for a new gun to have undergassed issues if there is enough bleeding.

Adjustable Gas Blocks always bleed so they often need more gas to run the system properly.

As far as your original question about the misalignment of the gas tube port in the gas block port. I see it often.

It could be the gas block or gas tube that's not in spec. In these cases I find a # drill bit that snugly fits the gas passage in the gas block. Install the Gas Tube a d Roll Pin and then insert the drill bit and manually try to deburring the gas tube port overhanging in the gas path. Dont use a powered drill as you can drill through the gas tube.

You want an unobstructed gas path from the barrels gas port to the gas tube. No overlapping or misalignment.
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Old September 16th, 2018, 03:27 PM #16
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Pic #1 carbon fouling around the spring and roll pin on an SLR GB
Pic #2 see 'blown' pattern of carbon on the barrel just in front of the block(arc pattern)?
Pic #3 fouling around another SLR GB(it even appears inside the cut-out).

I wouldn't sh!t you. No reason to.
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Old September 16th, 2018, 03:34 PM #17
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Originally Posted by clandestine View Post
Outrider is correct.

You want an unobstructed gas path from the barrels gas port to the gas tube. No overlapping or misalignment.
Exactly what I was trying to ask. Lol, now I'm just worried about the block exploding on me as it was only $18 and probably made in China.
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Old September 16th, 2018, 03:40 PM #18
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Exactly what I was trying to ask. Lol, now I'm just worried about the block exploding on me as it was only $18 and probably made in China.
It won't blow up. Even chinesoim steel is strong enough for this application.
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Old September 17th, 2018, 04:46 AM #19
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Listen to Outrider and Clandestine. They're spot on.

The gas tube doesn't need to be boot camp clean to function properly. Even if it leaks a little, if it's functioning, then that's just a cosmetic issue that a rag will take care of. As they said, it will be self healing if you don't soak it with cleaners and/or spray it with carb cleaner anally.
Get your holes lined up and go shoot. If your gas block seals to the barrel OK and the holes are aligned, then she'll probably be fine.


Quote:
Originally Posted by pidevildog07 View Post
I'm just having a hard time believing that carbon fouling is going to hold back a force of 45k+ psi.
If it makes you feel better, you'll only see a bit over 1/3 of that in a Carbine length gas system according to NSWC Crane testing of the M-4 Carbine. Here's a link to a presentation about testing 14.5 inch barrel uppers for reliability and performance due to changes in the gas system length. M855A1 5.56mm Ball was used for testing.
https://partner-mco-archive.s3.amazo...1527866983.pdf

Port Pressure 7.8 inches in front of the Bolt Face 17,000 PSI
Port Pressure 13 inches in front of the Bolt Face 10,000 PSI.

P.S. I did attend Armorer's School when in the Marine Corps in a past life, though I have never stayed in a Holiday Inn Express, ever. Hence, I think I'm right, but not the final authority on everything AR.
I believe Clandestine works on and builds them for a living.
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Old September 17th, 2018, 11:58 AM #20
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Originally Posted by K-43 View Post
Listen to Outrider and Clandestine. They're spot on.

The gas tube doesn't need to be boot camp clean to function properly. Even if it leaks a little, if it's functioning, then that's just a cosmetic issue that a rag will take care of. As they said, it will be self healing if you don't soak it with cleaners and/or spray it with carb cleaner anally.
Get your holes lined up and go shoot. If your gas block seals to the barrel OK and the holes are aligned, then she'll probably be fine.




If it makes you feel better, you'll only see a bit over 1/3 of that in a Carbine length gas system according to NSWC Crane testing of the M-4 Carbine. Here's a link to a presentation about testing 14.5 inch barrel uppers for reliability and performance due to changes in the gas system length. M855A1 5.56mm Ball was used for testing.
https://partner-mco-archive.s3.amazo...1527866983.pdf

Port Pressure 7.8 inches in front of the Bolt Face 17,000 PSI
Port Pressure 13 inches in front of the Bolt Face 10,000 PSI.

P.S. I did attend Armorer's School when in the Marine Corps in a past life, though I have never stayed in a Holiday Inn Express, ever. Hence, I think I'm right, but not the final authority on everything AR.
I believe Clandestine works on and builds them for a living.
Not at all worried about how it looks. None of my guns are safe queens. My concern was that of the gas tube showing a bit of its surface in the way of the gas exiting the port on the barrel and it causing undue stress on the gas tube and causing a short stroke from too much gas prematurely exiting the block before it reached the bcg.

I too was a 2111. Reserved to 2nd echelon till my eas though. If anything, I know more about foreign weapons from being in 29 palms, Camp Wilson, ATG. The only time I can recall having to dick with the gas system on an m4 is when someone was having trouble with cycling and the problem ended up being a clogged gas key from trying to use qtips instead of pipe cleaners to clean it.

Wow. I think I just partly answered my own question lol.
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