AR-15 Gas Tube Question

P

pdhntr

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I am going to set back one of my AR-15s. It has a rifle length gas tube on it now.

What are my options for making the gas tube shorter. I don't know of any way to make a new "collar" for the rear, so the only place seems to be the front.

1. The front has a plug that is crimped in place. Do I cut off the excess, and try to re-crimp the plug in place and then re-drill the hole in the right place?

2. Try to bend an "S" in the tube (without kinking) between the gas block and the receiver? I have done this already and it's not as easy as it sounds.

3. Other options?

Thanks.

Jim
 
Setting back an AR barrel is not a practical option, buy a new barrel.
 
TRA said:
Setting back an AR barrel is not a practical option, buy a new barrel.
Click to expand...

Maybe I should have given more information then.

It is a very expensive SS Krieger with less than 200 rounds.

I am not going to throw it away.

I believe it was chambered improperly.

Jim
 
20 inch barrell? easy, buy a carbine length tube. The "collar" your talking about i believe is the barrell extension. Buy one of them as well, and cut it to 16 inches and build it up as a carbine.

Other options are to remove the tube from the gas block/front sight and cut that end of the tube, then redrill the tube for the retaining pin.

If you want to try bending one, get a set of brake line tubing benders from napa. Thats the only way I know you can bend one without kinking it.
 
ok several options....
go from 20 to 16 and use a carbine gas tube...
the collar he is talking about is the expansion of the tube end to match sorta seal with the "key" on the carrier
if just going shorter..yes one can remove the pinned end insert, shorten the tube redimple in place and redrill.
the next one i do i am going to not worry about the gas port....drill tap and plug the old port if it does not line up and re drill an new port...

mike in co
 
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Mid-length barrel(18") is another option. Gas tubes can be bought for that length. Mid-length works better than the carbine length with the AR's gas system, as the barrel port pressure is closer to the original design.

RWO
 
Thanks guys.

I didn't know if there was anything out in the market place that I had missed when researching again.

Mike: I am not at the point I would feel confident in filling and re-drilling, but that is an interesting solution.

I think I will cut the front end to length and go that route.

Always good information. Thanks again.

Jim
 
hack yourself ......quite practical for the competent.
he was already talking about how to do the gas tube ...that should give you a clue.
i have been doing them for years.
in the book black magic they talk about doing one..that was published in 1998....
maybe you should ask questions first.....
i suppose you buy factory ammo, cause it aint "practical" to reload.
used high power bbls make great 18/16" short gun bbls.
mike in co
TRA said:
The key word was "practical", not impossible. Hack away.
Click to expand...
 
another option on the tube is to silver solder a sleeve over a butt joint....
cut the tube in half...shorten one pc to get desired oal...then have a shop silver solder a slightly larger tube over the joint/ends of the two pcs....and easy way to make a tube for a longer gas port...use two tubes and butt joint with an over tube.

mike in co
 
pdhntr said:
Maybe I should have given more information then.

It is a very expensive SS Krieger with less than 200 rounds.

I am not going to throw it away.

I believe it was chambered improperly.

Jim
Click to expand...

Can't you get someone to check the chamber before surgery? Krieger is located in Richfield, Wisconsin, and they are familiar with AR barrels and chambers. A phone call costs almost nothing.
 
yes...i'd like to hear what the issue with the chamber is ??
20 is typically a cmp/dcm across the course gun.
typically a hybrid throat with min rather than max chamber( no min spec just ton max)
so what is the issue ?

mike in co
 
Not much of an AR man, but something on the side of my old 721 might work. There are some small shoulder screws that plug the two holes that are used when mounting a peep sight. I think they are 6-48. Those would be perfect for plugging the existing hole in the barrel so you could drill another........jackie
 
When I built my AR-15, the gas tube I had was too short. I ordered a longer one from Brownells, but in the meantime, I went to the auto parts store and bought a brake line. Cut it to the length that I needed turned it down to match the ends of the shorter gas tube, plugged the block end, installed it in the gas block and drilled the cross pin hole, installed the roll pin and drilled the gas port hole in the tube. Worked like a charm and is still on the rifle even though the new tube came in a few days later. It's just a tube and nothing hard to do about it.
 
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mike in co said:
yes...i'd like to hear what the issue with the chamber is ??
20 is typically a cmp/dcm across the course gun.
typically a hybrid throat with min rather than max chamber( no min spec just ton max)
so what is the issue ?

mike in co
Click to expand...

Mike and Aero,

Once again I should have given more information. Sorry about that.

It is a 26" Krieger that was chambered in 20 Practical. The reamer is mine, and I took the reamer and barrel to a local gunsmith that has been doing my work for many years. I helped and watched while he did the chambering. This took place about a year and a half ago. I don't feel it is right to critique his methods on the internet, but I have learned a lot since then, and I have my own lathe and the tools to do a better job now. I would rather not discuss his method of chambering.

I have all intentions of checking the chamber before I change anything. I have the rods to get the bore lined up and the spider to help align the bore. I also built a floating pusher with the help of many on this site. None of these were used to chamber it originally.

The accuracy is half inch at 100 yds at best. That is with singly loading the rounds, not stripped from the mag. I can still shoot better than that with other rifles that I have. I have tried many different powders and bullet combinations and I just think that it might be the chamber is a little off.

I have the tools, and I think I should check the chamber to see what it is like.

My original question is (just in case) I find it is off and decide to rechamber, I wanted to get some prior knowledge about shortening the tube.

I hope this helps explain where I am at with this. I should have said I am thinking about setting it back in my first post. My apologies.

Thanks for everyones help.

Jim
 
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I would still like to answer some other post in this thread, but I have to get to bed. I have to work tomorrow.

I will pick this back up in the morning.

Jim
 
I realy doubt your gonna improve much on 1/2 inch out of an ar by re chambering the rifle. I would take those groups all day long, and make High Master and Distinguished with that gun, if it was in 223 of course
 
The bell on the end is actually the same size as the rest of the tube, not an expansion of the tube. The tube is just reduced forward of the bell for a couple inches.

We have unfinished tubes on hand for just such odd applications. The forward end is plugged and drilled, but the tube is not bent and they are about 20' long. Just cut to length, stick them in the lathe and turn the reduction to form the bell on the end, and bend with a cheap hardware store tubing bender. Give me a holler if you need one.

Do not use brake line.

To remove the old chamber you will need to cut about 2" from the barrel. I do not think I would want a 24" barrel with a gas system 2" shorter than std rifle length. Might work, but I am afraid it may be hard on brass due to the dwell time. I would consider cutting 6" off the fr0ont end also and making a 18" barrel out of it. Be a nice handy coyote gun.

Imagine 20 years ago someone complaining that their semi-auto plastic and aluminum army rifle was only shooting 1/2 MOA. My how far we have come.

John
 
Mike Bryant said:
When I built my AR-15, the gas tube I had was too short. I ordered a longer one from Brownells, but in the meantime, I went to the auto parts store and bought a brake line. Cut it to the length that I needed turned it down to match the ends of the shorter gas tube, installed it in the gas block and drilled the cross pin hole, installed the roll pin and drilled the gas port hole in the tube. Worked like a charm and is still on the rifle even though the new tube came in a few days later. It's just a tube and nothing hard to do about it.
Click to expand...

Hi Mike,

Great idea. But I am re-thinking the whole works.

It will be outlined soon in the following post.

Thanks.

Jim
 
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