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View Poll Results: Which AR15 gas tube length is functionally superior?
Carbine length...usually 7" as I understand it 0 0%
Mid-length...usually 9" as I understand it 16 100.00%
Voters: 16. You may not vote on this poll

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Old February 19, 2009, 03:36 PM   #1
Te Anau
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AR15 mid-length gas tube.

I have looked at the possibility of getting an AR15 for years now but have never been able to actually get out the wallet and do the deed.Just recently I became aware of the carbine vs mid-length gas tube situation and just want to see what others think.I've decided that if I do it this time (get that stinkin' AR once and for all) I'm going with the mid-length if for no other reason than it looks better IMHO.I guess this will be one of those debates that goes on forever.
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Old February 19, 2009, 04:34 PM   #2
zoomie
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You can put mid-length or even rifle length handguard on a carbine rifle, so either system can look however you like. The midlength is a little less violent and should theoretically lead to longer parts life. I think you'd have to shoot a whole helluva lot to notice any difference in failure rates. Mine are both midlength and I like em that way.
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Old February 19, 2009, 05:29 PM   #3
GLK
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Quote:
You can put mid-length or even rifle length handguard on a carbine rifle, so either system can look however you like. The midlength is a little less violent and should theoretically lead to longer parts life. I think you'd have to shoot a whole helluva lot to notice any difference in failure rates. Mine are both midlength and I like em that way.
I am not sure what you mean Zoomie, but Te Anau will need a barrel with the gas port drilled in the mid length position in order to use a mid length gas tube. I have both mid length and carbine systems and much prefer the mid, it may be psychological but I do better with the mid length gas system.
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Old February 19, 2009, 05:31 PM   #4
zoomie
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Quote:
I am not sure what you mean Zoomie, but Te Anau will need a barrel with the gas port drilled in the mid length position in order to use a mid length gas tube.
Right. But I didn't say gas tube. I said handguard.
Quote:
You can put mid-length or even rifle length handguard on a carbine rifle
He can make a carbine gas system look like a midlength gas system on the outside by installing a midlength handguard over the gas block.
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Old February 19, 2009, 06:13 PM   #5
TheManHimself
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What it boils down to is that the Stoner gas system operates best when the gas port is located the correct distance from the muzzle for proper dwell time (Which is why SBRs shorter than 14.5" can be so finicky).

The AR-15 rifle was originally designed around a 20" barrel with the rifle-length gas system. When the military standardized on a 14.5" carbine barrel, they shortened the gas system to 7" to maintain proper dwell time.

Unfortunately, since the commercial sector has to produce 16" barrels for their Title I weapons, rather than producing 16" barrels with the proper gas port location, many manufacturers simply copy the M4 design but add a longer barrel; the increased dwell time means that the action cycles more violently, and that the chamber pressure is higher when the bolt unlocks, putting undue stress and wear on parts. Their unnecessary use of lighter bolt carriers, buffers, and weaker extractor springs than what the mil-spec calls for only exacerbates the potential for extraction/ejection issues.

The midlength (9") gas system was developed to rectify that. A 16" barrel with mid-length gas results in the same dwell time as a 14.5" barrel with carbine-length gas or a 20" barrel with rifle-length gas.

The mid-length gas system is unarguably superior to the carbine-length gas system on a 16" barrel. Less wear on parts, easier extraction, and less muzzle rise, with no downside. Midlength gas barrels typically are little or no more expensive than a carbine-gas barrel from the same MFG.
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Old February 20, 2009, 02:15 PM   #6
Te Anau
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Well good,it sounds like mid-length is the way to go.
Thanks
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