Changing gas tube length

Jdiep

Jdiep

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Hey gun nuts!

I just had a 20" barrel on my ar and I'm switching to a 14.5" . Oviously the gas tube is too long. Could I just cut the end and ream it to fit or should I buy a new one?

Thanks. This is probably a newb question.
 
To have it operate correctly purchasing the appropriate size is the recommended course of action. The end of the tube is precisely flared to seal the connection between the gas key and tube so any deviation in this will result in poor functionality.
 
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You can't just cut it down. One end is precisely machined and the other has a plug machanically sealed in. Cutting it down would eliminate either of those features and they would need to be replaced. Spend the $15-$30 and buy the right size one.
 
As pointed out above, just spend the $15-$20 on a new tube. Gas tubes have a slight bulge "mushroom" at the tip of the tube that goes into the bolt carrier. This bulge helps create a seal in the gas key so that sufficient gas can cycle the carrier. It might not make a whole lot of difference with a heavily over gassed system but why chance it to save $20.?

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I'm quite sure Tier One Armory in Edmonton has them in stock and they're within driving distance. it's a little store, but its mostly AR15 stuff, great guys to deal with.
 
Blastattack said:
You can't just cut it down. One end is precisely machined and the other has a plug machanically sealed in. Cutting it down would eliminate either of those features and they would need to be replaced. Spend the $15-$30 and buy the right size one.
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Actually you can just cut them down. Done it many times. It works just fine. The rear end is not precision machined. It just has to fit inside the gas key nose.




Phat Eagle said:
This^^^ It will not run if cut down.
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It will. Done it dozens of times.
 
Not to be an a$$hole, but most of you have no idea what you're talking about. (Suputin's on the right track).

I don't suppose anyone in this thread has ever actually measured the 'mushroomed/flared' end of a gas tube?

I assume not, because it's not mushroomed or flared. It is the same diameter as the rest of the tube. They turn the diameter down slightly ahead of the end and they put a chamfer on the end. That's it.

So it may look like it's flared or mushroomed, but it's not.

I have cut carbine tubes shorter to make pistol length tubes, and they work just fine. You don't even have to relieve the area ahead of the end. It still works.

The chamfer on the end helps guide it into the gas key.

There's not even that good of a 'seal' between the gas tube and gas key to begin with. There's at least .007" diameter clearance, sometime more depending on the manufacturer. So essentially no seal whatsoever.

Don't believe me? Grab your micrometer and gauge pins and prove me wrong........
 
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Suputin said:
Actually you can just cut them down. Done it many times. It works just fine. The rear end is not precision machined. It just has to fit inside the gas key nose.







It will. Done it dozens of times.
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Overgassed AR systems will cycle anything and having severely modified pieces on an AR is not the best practice. Yes anything can be accomplished on a mechanical item however this modification must never be attempted on a rifle used for patrol or protection.
 
Jdiep said:
Hey gun nuts!

I just had a 20" barrel on my ar and I'm switching to a 14.5" . Oviously the gas tube is too long. Could I just cut the end and ream it to fit or should I buy a new one?

Thanks. This is probably a newb question.
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Ream what to fit? The inside diameter of a gas tube is the same from front to back. I'm not sure what you would ream.........
 
Jdiep said:
To take out the burr inside after you cut it. Also if I do cut it. How far does it go into the upper?
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You don't need a reamer to deburr the end. A small chamfer or (by hand) twist the end of a larger diameter drill bit against it and that will get rid of the burr.

As mentioned previously, the bend is your real problem, it has to be done with a little bit of finesse to get the offset right and not kink it.

Carbine gas tube is 9.75" long.

My advice (for the nothing it's worth): If you're never going to need a rifle length gas tube, cut the thing to fit and see if she works. If it does, you're golden and you learned a new skill. If it doesn't, you go buy a gas tube and you're out $20 and a gas tube you were never going to use (although I suppose you could have sold it).

If you DO plan on needing a rifle length gas tube in the future, put that one aside and buy a new one.

If you're just so horny to shoot your ar15 at all costs and don't wanna wait for either, shift your gas block forward (unless it's pinned of course) and shoot it single shot
 
Sqr said:
Overgassed AR systems will cycle anything and having severely modified pieces on an AR is not the best practice. Yes anything can be accomplished on a mechanical item however this modification must never be attempted on a rifle used for patrol or protection.
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And of the AR's owned by people on this board, just how many are used for "patrol or protection?" I'd suggest not a single one. Nice try though.
 
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