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7/16/2011 5:23:17 AM EDT
What is shortest barrel can one use with a midlength gas system?
7/16/2011 6:56:44 AM EDT
[#1]
Quoted:
What is shortest barrel can one use with a midlength gas system?


The shortest I'VE seen is a 14.5" barrel.

Let's do a little math here. Handguards on a carbine are 7", and the shortest barrel I've ever seen on a carbine gas system is 10.3". SO..... midlength guards are 9", so in theory you may be able to go to the 12-12.5" range? This would probably be custom and you would have to have the gas port worked on to function properly, but it may be doable.
7/16/2011 7:39:34 AM EDT
[#2]
Isn't the Kino a 12.5" midlength?
7/16/2011 7:41:28 AM EDT
[#3]
I've contemplated cutting mine to 12.5" for almost 3 years now and using it as a dedicated suppressed upper. my plan was to not open the gas port at all and let the massive amount of blow back from the can supply the needed dwell time to operate. I'm fairly positive you'll need to open the port if you're looking at 12.5" and no can.  you'll likely be okay in the 13.2"-14.5" range with your standard gas port size. My midlength was cut at 14.5" and pinned with an m42k blackout mount years ago. IICR, the port wasn't opened.
7/16/2011 7:43:10 AM EDT
[#4]
Quoted:
Isn't the Kino a 12.5" midlength?


just the fsb, gas is carbine
7/16/2011 7:54:15 AM EDT
[#5]



Quoted:



Quoted:

Isn't the Kino a 12.5" midlength?




just the fsb, gas is carbine


Ah yeah, you're right.  Been a while since I looked into one.



 
7/16/2011 10:05:29 AM EDT
[#6]
Quoted:
Quoted:
What is shortest barrel can one use with a midlength gas system?


The shortest I'VE seen is a 14.5" barrel.

Let's do a little math here. Handguards on a carbine are 7", and the shortest barrel I've ever seen on a carbine gas system is 10.3". SO..... midlength guards are 9", so in theory you may be able to go to the 12-12.5" range? This would probably be custom and you would have to have the gas port worked on to function properly, but it may be doable.


This is what I was thinking.

You need 9" plus the gas block plus enough to thread for the muzzle device.

I think 12-12.5 is the correct answer.
7/16/2011 11:17:38 AM EDT
[#7]
Quoted:
Quoted:
Quoted:
What is shortest barrel can one use with a midlength gas system?


The shortest I'VE seen is a 14.5" barrel.

Let's do a little math here. Handguards on a carbine are 7", and the shortest barrel I've ever seen on a carbine gas system is 10.3". SO..... midlength guards are 9", so in theory you may be able to go to the 12-12.5" range? This would probably be custom and you would have to have the gas port worked on to function properly, but it may be doable.


This is what I was thinking.

You need 9" plus the gas block plus enough to thread for the muzzle device.

I think 12-12.5 is the correct answer.


Actually, if you didn't run an FSB, you could use a shorter gas block and probably come back a little more (I think the VLTOR block is only 1" long). The issue would be having enough barrel PAST the gas port to give sufficient dwell time for proper cycling. I don't know what that number is.
7/16/2011 11:24:53 AM EDT
[#8]
My buddy has a 12.5" middy. Great shooting gun.

It has the same dwell time as a 10.5" carbine gas and 16" rifle gas. All reliability issues can be solved with quality parts and MAYBE some gas port work.
7/20/2011 7:13:38 AM EDT
[#9]
I took a 16" stainless noveske recon barrel which is a midlength gas system and cut it down to a 11.5". Before we opened the gas port it would only cycle with a supressor on and the switchblock turned all the way on. It would cycle with the switchblock switched to supressed but wouldn't lock back on the last round. Without a supressor it wouldn't cycle at all. We opened the gas port, if I recall and I dont have my notes with me, about 8 drill sizes before it was all done. Now it runs perfect without the supressor. With the supressor on with the switchblock on the supressed setting there is still alot less gas than on wide open, so the switchblock is still serving it's purpose. Hope that info helps. If someone would like the exact drill size I will post it when I get home.

7/20/2011 7:07:08 PM EDT
[#10]
Quoted:
I took a 16" stainless noveske recon barrel which is a midlength gas system and cut it down to a 11.5". Before we opened the gas port it would only cycle with a supressor on and the switchblock turned all the way on. It would cycle with the switchblock switched to supressed but wouldn't lock back on the last round. Without a supressor it wouldn't cycle at all. We opened the gas port, if I recall and I dont have my notes with me, about 8 drill sizes before it was all done. Now it runs perfect without the supressor. With the supressor on with the switchblock on the supressed setting there is still alot less gas than on wide open, so the switchblock is still serving it's purpose. Hope that info helps. If someone would like the exact drill size I will post it when I get home.



Thanks for all the responses.  This is prbably what I am going to do.  Please let me know what the exact drill size is.

7/21/2011 10:55:28 AM EDT
[#11]
Quoted:
I took a 16" stainless noveske recon barrel which is a midlength gas system and cut it down to a 11.5". Before we opened the gas port it would only cycle with a supressor on and the switchblock turned all the way on. It would cycle with the switchblock switched to supressed but wouldn't lock back on the last round. Without a supressor it wouldn't cycle at all. We opened the gas port, if I recall and I dont have my notes with me, about 8 drill sizes before it was all done. Now it runs perfect without the supressor. With the supressor on with the switchblock on the supressed setting there is still alot less gas than on wide open, so the switchblock is still serving it's purpose. Hope that info helps. If someone would like the exact drill size I will post it when I get home.



Interesting. But I've got to ask... aside from just doing something different, do you see any real benefit vs a 11.5" carbine?
7/22/2011 11:50:11 AM EDT
[#12]
tag for drill size

sounds like it'd shoot softer than a 10.5" carbine too, right?
7/22/2011 3:39:47 PM EDT
[#13]
Quoted:
Interesting. But I've got to ask... aside from just doing something different, do you see any real benefit vs a 11.5" carbine?


Yes there is a difference. Let me explain what I have come up with from my two different SBR's. I have the 11.5" with midlength with SB that runs a Vortex Gemtech G5 adapter and I have a standard 10.5" chromelined FSB gun with a Surefire K muzzle brake on it. I do feel a difference when shooting the two, even with the brake the midlength 11.5" gun seems to run moore smooth and less jerky recoil. Now with that being said it's definitely not a huge difference. And to throw it back to a more personal note I just wanted to run a 9" handguard with a switchblock and didnt want to buy a complete Noveske upper as it didnt have the rail that I wanted available.

The drill size was # 41, decimail size is .960

TX556DE

8/6/2011 1:04:08 PM EDT
[#14]
One of my SBR uppers is a 12.5 in 6.8 with a mid length gas system and 9" LaRue Quadrail. I also run a 7.62 phantom on it and it runs fine.

M.
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