Gunsmithing AR-15 build loose gas tube.

[NoomaScout]

I am in the middle of an AR-15 build and I noticed the gastube is loose in the receiver end, but is nice and secure at the gas block end. Please note it is loose to the point of rattling. The receiver is made by LARUE and is the Stealth model, the barrel is a BHW 18’’ and the gas tube is rifle length.Troy gas block and a Noveske NSR hand guard. I have not had this issue before and have checked my other uppers and all the gas tubes are tight with no movement. Has anyone on the forum experienced this issue, if so what was the fix? Thanks.

 

[mallrat]

Tag. I haven't had that problem, but it'd be good to know the proper solution in case I do later.
Might be able to center it using a high-temp o-ring.

 

[George Az]

Some rattle, I had a Colt match target that rattled from day one, but shot very well. As long as the carrier key does not have an issue with cycling - this is the most important thing on 'franken guns". And no insult to you. I have built and had my share of problems with some I have built. The carrier key must smoothly cycle or you are going to have real problems. Some times the gas tube can be slightly twisted and it might help a little bit.

I would disassemble everything and make sure it is all lined up. Good luck.

 

[ORD]

A little bit of "wiggle" or movement of the tube isn't a bad thing and actually, it is pretty normal for rifle-length tubes in my experience. If you have the barrel nut perfectly aligned (as you should), then there is nothing for the tube to bind against or keep it from moving slightly. Same thing for the "cloverleaf" pass-through for the tube into the upper if it is indeed in spec. Ultimately, a little bit of movement or float to the tube gets everything aligned in terms of the gas tube to the carrier key. That said though...one man's "rattle" is another man's "normal" so its tough to tell whether you have a problem or whether its no big thing. I'd suggest running the rifle and see if you experience any function/accuracy issue with it before chasing ghosts in the machine that may have zero impact on how your rifle runs. But with that said...

What, specifically, does the tube appear to be "rattling" against?

When does it rattle (all the time, when the carrier is in/out of the rifle, etc.)?

How much movement are you talking about and in what direction(s) are you noticing it?

If it is indeed secure/tight in terms of the fitment at the gas block where it is pinned in place, and the gas block itself is properly secured to the barrel where it fits snugly at the journal (no loose ends, slop, etc. between the block and the journal on the barrel), and the barrel itself is properly secured to the upper receiver and the extension on the barrel isn't loose, then its likely one of a few issues, none of which should be of concern unless the proper function/accuracy of the rifle is somehow impaired.

1) the gas tube itself could be slightly bent causing it to seemingly "rattle" against one side of the upper at the cloverleaf where it enters the receiver, bbl nut, etc.;

2) the cloverleaf in the upper receiver is out of whack/spec. and allowing the gas tube to bang around against one side/portion of it.

In any event...try running the rifle for function first. If it functions properly, run for accuracy. If everything checks out with both...leave it alone. If something is awry...well...deal with it in turn.

Good luck!

 

[Deadshot2]

In any event...try running the rifle for function first. If it functions properly, run for accuracy. If everything checks out with both...leave it alone. If something is awry...well...deal with it in turn.

Good luck!

Absolutely the first step. If the "rattle" is absolutely driving you nuts you can use a SMALL amount of high temp silicone sealer (the kind used attach the glass rope seals on an air-tight stove) around the tube where it passes through the upper. Just apply it with the end of a Q-tip that you've cut the cotton end off of. Put some of the silicone on the end of he "q-tip shaft" and press the goop into the void around the tube. Repeat so there's some of the silicone sealer on each side of the gas tube, as even as possible. Then release the bolt carrier group and find something else to do until it's cured. Be sure to use the high-temp silicone if you want this fix to last.

When it comes time to remove or replace the gas tube the silicone will just come out with the tube or can be pushed out with a q-tip. You're just making your own "washer/o-ring".

Me? I just shoot whatever is working and don't worry about little rattles. What's a small rattle compared to all the other noise associated with a rifle?