Mid length gas system vs. carbine length
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Old 02-20-2012, 06:14 AM   #1
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Default Mid length gas system vs. carbine length

I am looking to get my first AR. I have been doing my research for a few weeks and have a question. What are the differences ( other than the length ) of mid length and carbine length gas sytems? Are there advantages to either? I am looking at Rock Rivers. I will mostly be plinking at the range with some coyote / praire dog hunting thrown in.

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Old 02-20-2012, 06:45 AM   #2
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Originally Posted by sparky17 View Post
I am looking to get my first AR. I have been doing my research for a few weeks and have a question. What are the differences ( other than the length ) of mid length and carbine length gas sytems? Are there advantages to either? I am looking at Rock Rivers. I will mostly be plinking at the range with some coyote / praire dog hunting thrown in.
Main purpose of the carbine length gas system was to allow sufficient pressure to remain in the barrel to cycle the bolt on the original military M4 equipped with a 14" or shorter barrel. No real advantage to having it on a civilian AR other than retaining the M4 look. It will generally have a sharper recoil impulse than a mid length or rifle length system, but that can be mitigated with a heavier buffer. A shorter gas system will also shorten the sight radius if you use a standard A2 type FSP. Personally, of the three I prefer the mid-length as it has a softer recoil and offers more foregrip and sighting choices without necessarily having to go to a lo pro gas block.
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Old 02-20-2012, 09:00 AM   #3
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The "carbine length" gas system was used on the 16" guns way before the M-4 was dreamed up. What ever gas system is used, it must have a gas port drilled to balance gas system length, barrel length and gas port size. The carbine length or mid length can be used on a 16" barrel but the port size will be different.

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Old 02-20-2012, 02:54 PM   #4
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Unless you have a lo profile gas block a free float a oversized rail/hanguard over it:

Middys have 2 inches more rail to hold onto, and 2 inches more sight radius, but trade of off a little eight for it.

IMHO since most manufacturers over gas their systems, the whole smoother cycling thing is a moot point.

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Old 02-20-2012, 04:57 PM   #5
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What barrel length are you looking at? What kind of ammo, Wolf or high powered or everything? Which buffer weight will you get? AR or M16 bolt carrier? Does your manufacturer choose the best gas port size for each system? There are advantages to each gas system length but you need to fill in more blanks before choosing which is best for you. If it comes down to a tie I'd go with the longer gas system if it will reliably cycle your rifle.

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Old 02-20-2012, 07:41 PM   #6
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What barrel length are you looking at? What kind of ammo, Wolf or high powered or everything? Which buffer weight will you get? AR or M16 bolt carrier? Does your manufacturer choose the best gas port size for each system? There are advantages to each gas system length but you need to fill in more blanks before choosing which is best for you. If it comes down to a tie I'd go with the longer gas system if it will reliably cycle your rifle.
Barrel length is 16". Shooting mostly handloads since I also have Remington 700 bull barrel 223. Buffer and bolt carrier (AR?) would be standard for Rock River Arms.
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Old 02-21-2012, 08:59 PM   #7
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Barrel length is 16". Shooting mostly handloads since I also have Remington 700 bull barrel 223. Buffer and bolt carrier (AR?) would be standard for Rock River Arms.
Back in the late '90's, there was someone who was making pigtail shaped gas tubes to increase the length of the tube so the carbine would be the same length tube as a 20 inch barrel. I don't know if it worked, or people didn't want to spend some time and money finding out.
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Old 02-22-2012, 01:24 AM   #8
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Back in the late '90's, there was someone who was making pigtail shaped gas tubes to increase the length of the tube so the carbine would be the same length tube as a 20 inch barrel. I don't know if it worked, or people didn't want to spend some time and money finding out.
From what I've read it didn't do much, an extra 2" of gas tube had little effect. What makes the difference is where the gas port is on the barrel.
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Old 02-22-2012, 02:36 AM   #9
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Originally Posted by fsted2a View Post
Back in the late '90's, there was someone who was making pigtail shaped gas tubes to increase the length of the tube so the carbine would be the same length tube as a 20 inch barrel. I don't know if it worked, or people didn't want to spend some time and money finding out.
I think Brownells still sells those
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