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Changing gas system on a carbine. Going from Carbine length to rilfe l


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#1 Julien Boit

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Posted 23 April 2013 - 12:43 PM

Hi all,
I have a technical question that may sound weird but here it goes :
Is it possible to change a factory carbine length gas system to a rifle length gas system ?

I have this in my mind for quite some time and I want to have opinions, here is how I would do :

- Plug the current gas port in the barrel with a steel ball , and modify the current gas block to have a screw on top of the steel ball to secure it.
- Drill a new gas port at the right location (rifle length).
- Put a new gas block at the new location (maybe an adjustable one).
- Make a new gas tube that would pass by the old gas block and go back into the upper receiver (Taking a rilfe length tube should do the trick with some bending).

What you guys think about that ? This is purely theoric (for the moment ?) but do you think it is doable ?
I know putting a new barrel with the right gas system woule be easier, but hey, I have spare time ;-)

#2 grouse

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Posted 23 April 2013 - 01:48 PM

Not worth it. Sell the barrel and buy a new one

#3 mpom

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Posted 23 April 2013 - 05:55 PM

unless you have a machine shop and the skill to do this, your money would be better spent in buying a new rifle gas barrel and gas block, in my opinion.

mark

#4 caspian guy

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Posted 23 April 2013 - 07:58 PM

I gotta ask why?

having said that if I had to do it, I think I'd tap the existing gas port for a short grub screw. Then I'd install it with permanent locktite. following that I'd probably turn a small collar on my lathe to slide over the barrel to cover the plug and lock it down ( maybe use a set screw on the bottom of the collar to secure it). You could probably use a small low profile gas block as a collar if you wanted.

I think adco does something like this and maybe puts a tack weld on the plug to keep it from backing out? You could email them and ask...

My other question would be is the diameter where you were planning on putting the new gas port large enough for a standard gasblock? (I suppose if it wasn't you could turn it down to the next smallest size, or make a custom gas block)?

#5 Julien Boit

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Posted 23 April 2013 - 11:34 PM

unless you have a machine shop and the skill to do this


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#6 Bearcave

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Posted 24 April 2013 - 10:44 AM

Brownells has a pigtail gas tube, rifle length tube for carbine length gas port. Don't know about the export part if you are in France. You have the machine shop handy may be able to make one of them.
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#7 broke_again

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Posted 24 April 2013 - 07:28 PM

Is the barrel the correct diameter at the point you want to put the new gas block location?



#8 Julien Boit

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Posted 24 April 2013 - 11:44 PM

Is the barrel the correct diameter at the point you want to put the new gas block location?

 

Barrel is .750 at this location.


Edited by Julien Boit, 26 April 2013 - 12:18 PM.


#9 Chuck Anderson

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Posted 25 April 2013 - 04:35 AM

How long is the barrel? Most I've seen with carbine gas are 16" or shorter. That's not long enough for a rifle gas system. The port would have to be larger than usual because of the short dwell time past the port. You'd end up with all, and more, of the issues of a carbine system just at greater expense. The shortest rifle gas barrels I've seen are 17" and most are 18"+.

#10 Julien Boit

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Posted 26 April 2013 - 01:25 AM

The barrel is a 14.5 inches M4 profile.

I aslo thought about putting a pigtail gas tube and/or an adjustable gas block.



#11 caspian guy

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Posted 26 April 2013 - 03:12 AM

At 14.5" I think you'd have a hard time making anything longer than midlength work. (even that would likely be under gased).

#12 Chuck Anderson

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Posted 26 April 2013 - 04:53 AM

You can do a pigtail but definitely not a rifle length gas system. You'd only have about 2.5 inches of barrel after the port. Even the 7.5 inch barrels which are a pain to tune right have 3.5. Even swapping to a mid length would not give you any benefit.

#13 Julien Boit

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Posted 26 April 2013 - 12:15 PM

All these thoughts lead me to one question :

What's the most important, the gas tube length, or the position of the port in the barrel ?

I mean, if the port is still located at the same spot (carbine length) but the gas tube is longer, is there any effect ?

 



#14 Steve RA

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Posted 26 April 2013 - 12:21 PM

I doubt it.


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#15 Alaskapopo

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Posted 26 April 2013 - 05:17 PM

All these thoughts lead me to one question :

What's the most important, the gas tube length, or the position of the port in the barrel ?

I mean, if the port is still located at the same spot (carbine length) but the gas tube is longer, is there any effect ?

 

It increases the dwell time and can help with the gun being over gassed or so the theory goes. I have never used one.

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#16 Croomrider

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Posted 02 May 2013 - 11:36 AM

I have done something similar to what you are trying to do and it worked fine. To plug the old gas port, just drill & tap 10-32 or something similar, but do not break through into the barrel which would open the hole in the barrel. Run an appropriate set screw in with red locktite and grind flush if desired. You can then locate the gas port where ever you want. I even made my own gas tube out of some thick walled SS tubing. I then experimented with the size of the port hole into the barrel to get the action to function smoothly without being violent. This is not rocket science and there are plenty of combinations that will work just fine. As a machinist, just go with your gut and don't let the part swappers tell you it won't work!

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#17 DaveTimm

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Posted 03 May 2013 - 05:55 PM

If I missed it I apologize as I'm on my phone but what is your goal? Do something different, softer felt recoil, cycling etc. One has to not only look at pressure of the has but also the dwell time. While not many would argue the pressure is high with carbine length, the dwell time is near perfect. It's a very reliable system. You certainly can proceed with the process but with that short of a dwell time you'd have to make that gas port huge. A big company use to make 16" disapators, 16 barrel with rifle length gas system and they had tons of issues. With a 14.5 itd be even worse. If your looking to soften felt recoil look at buffer and springs, comps etc. you might also really like the JP silent spring system.

#18 gixxerjunky

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Posted 03 May 2013 - 07:13 PM

Just sell your barrel and get a 14.5 middy. That's what I run with a H2 buffer without issue so far. I am running a DD barrel if that matters.

#19 Sako92S

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Posted 07 May 2013 - 12:34 AM

1. Sell the barrel and get new one or

2. Change the gas system to mid length. Use low profile gas block upside down on your old carbine gas place and then drill new hole for mid length gas.

 

I changed my system opposed way. The Remington barrel was 22" and it was cut down to 14,5" and new middy gas system was installed. :)

This is how it shoots now on 150m with 51gr Lapua CE bullet. :D

 

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#20 PatUSAF

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Posted 12 May 2013 - 11:39 AM

You can do a pigtail but definitely not a rifle length gas system. You'd only have about 2.5 inches of barrel after the port. Even the 7.5 inch barrels which are a pain to tune right have 3.5. Even swapping to a mid length would not give you any benefit.

Does the pigtail soften the recoil when installed on a carbine length system? Brownells makes it seem like its for solving FTF problems






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