Help! Broke AR gas tube?

[Brn N Rubr]

I took my AR out for the second time today. Red X Arms 16" pencil upper with lo-pro gas block, PSA lower. Nothing special. Just a decent paper puncher. I shot a few hundred rounds of steel case Monarch through it and everything was fine. A friend asked to shoot it and of course I obliged. He came back a minute later and told me it would fire, but not cycle. Upon closer inspection it appears the gas tube broke in the upper receiver. There also appears to be damage to the carrier key. What would cause this?

[phaux]

What ammo were you shooting?

[CJ]

Misaligned gas tube. Where did the end go?

[Brn N Rubr]

As stated in original post...we shot steel cased Monarch today.

No clue where the end went. That's my problem!

I did notice the nut at the back end of the quad rail was loose after shooting a while. Could that cause the misalignment?

[CJ]

As stated in original post...we shot steel cased Monarch today.

No clue where the end went. That's my problem!

I did notice the nut at the back end of the quad rail was loose after shooting a while. Could that cause the misalignment?

That nut pushes into the barrel nut to keep the rail from twisting, it shouldn't have anything to do with the gas tube. However, depending on how they assembled the gun, if they didn't get the nut aligned correctly and there was lateral tension when they pushed it through the receiver that might explain it. Take a look through the barrel nut and see if it's completely straight or not. The marring on your gas key is from the mouth of the gas tube smashing into it. Do you recall having an instance when you had to use the forward assist or it not chambering all the way? The reason you can't find the gas tube is it most likely was ejected along with a case. Another possible explanation is the gas block was not tight, the tube became misaligned, and when the gun chambered it knocked the gas tube along with the gas block forward out of the upper receiver. Have you checked your gas tube inside the handguard and the gas block? Is it in the right spot?

[Brn N Rubr]

There was no instance of having to use the forward assist. It ran flawlessly until my buddy tried it.

I can't see through the hand guard to see if the barrell but is aligned.

You feel like fixing it for me!?

[CJ]

There was no instance of having to use the forward assist. It ran flawlessly until my buddy tried it.

I can't see through the hand guard to see if the barrell but is aligned.

You feel like fixing it for me!?

I was waiting for that. Let's first see what the problem is. Loosen up the screws that are on the quad rail close to the receiver (I believe red x still uses utg quads) once that's done unlock the jamb nut and twist the quad rail off and take a picture. If you can't do that just put a bright light down the muzzle so we can see inside it and take a picture.

[Brn N Rubr]

I'll pull it out real quick and see what I can do.

[Brn N Rubr]

Well, I think I found part of the problem.....

[Brn N Rubr]

The set screws that hold the gas block in place are very loose with no sign of thread locker. Should it have some?

[Brn N Rubr]

The gas tube seems to be fine.

[CJ]

Yep just as I thought, it got knocked forward. slide it back on and tighten it. Standard thread locker stops working at 300 degrees. That gas block will be well over that in a few seconds. I have used those blocks and they dont come loose. Just tighten them. Thats one of your problems, just make sure that the gas tube is in line, as that could have been the first problem that caused this.

[Brn N Rubr]

Got the gun back together. All seems well. The bolt cycles cleanly with no hint of interference. Now, as long as the tube isn't cracked somewhere I can't see it should be good to go!

[likeitfast55]

Gas tubes are cheap. But your bolt looks fubared

[Brn N Rubr]

Thanks for the help, guys!

This is an honest question, what's the worst that could happen trying to use the bolt as is? Gases leak by and either a: doesn't cycle properly and b: fails to lock on the last round? Explode? Dangerous?