School Me: Mid-length v. Carbine length gas tube

[Timthetwin]

I am wondering what the main technical differences are between the two, and how that relates to types of ammo and accuracy

Thanks!

~TtT

[Checkk]

https://www.google.com/search?q=cabine+vs.+mid-legnth&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a&channel=sb#channel=sb&q=carbine+vs.+mid-length&rls=org.mozilla:en-US:official&spell=1

[thospb]

The difference is about time. Longer for the bullet to pass the Gas Port and longer for the Gas energy to reach the bolt. Micro seconds that are noticeable in the action of the weapon. Remember that the AR platform was originally designed for a 20" barrel and a Rifle length gas system, shorter barrels were adapted for portability not as an improvement on function.

[REDdawn6]

The difference is about time. Longer for the bullet to pass the Gas Port and longer for the Gas energy to reach the bolt. Micro seconds that are noticeable in the action of the weapon. Remember that the AR platform was originally designed for a 20" barrel and a Rifle length gas system, shorter barrels were adapted for portability not as an improvement on function.

Excellent answer. Thanks.

[Mossy Man]

Optimal reliability/wear setups:

14.5" - Carbine
16" - Mid
18" - Mid/Intermediate
20" - Rifle

You can run different gas systems on different lengths with different results.

For example, a 16" with a Rifle gas might be a really soft shooter, but it might be sensitive vs. low power ammo.

[Timthetwin]

Optimal reliability/wear setups:

14.5" - Carbine
16" - Mid
18" - Mid/Intermediate
20" - Rifle

You can run different gas systems on different lengths with different results.

For example, a 16" with a Rifle gas might be a really soft shooter, but it might be sensitive vs. low power ammo.

I get and know about the different lengths, I am wondering if someone can elaborate about those different results. Thanks fellas.

For example a 16" barrel with eight a mid length or carbine length gas system?

[mcisniper]

Short and dirty. the longer the gas system the smoother the rifle (everything else being equal). Middys are smoother than carbines and rifles/Dizzys are smoother than middys.

[caliberetta]

can a carbine gas system be made to behave like a middy through the use of an adjustable gas block?

[Ronin2]

Thanks for the answers... Into was curious.

[Oceanbob]

I have no direct experience with this but some shorty AR pistols use a coiled
Gas tube that is almost the length of a rifle gas tube.

http://vtsupply.com/phase-5-tactical-ar15-cqc-pistol-7-5-complete-upper-ar-15.html

Quote:

The pigtail gas tube was designed to solve timing problems for the 7.5" pistol barrels. Using a gas tube that is almost the length of a rifle gas tube, making the gas take longer to reach the gas key. Simulating a more standard cycle time and helps remedy the timing problems without patchwork like heavier buffer, ect. This allows the shooter/builder to use standard Mil-Spec carbine parts, making it more reliable, easy to maintain and more predictable.

[nothinghere2c]

I have no direct experience with this but some shorty AR pistols use a coiled
Gas tube that is almost the length of a rifle gas tube.

http://vtsupply.com/phase-5-tactical-ar15-cqc-pistol-7-5-complete-upper-ar-15.html

Quote:

The pigtail gas tube was designed to solve timing problems for the 7.5" pistol barrels. Using a gas tube that is almost the length of a rifle gas tube, making the gas take longer to reach the gas key. Simulating a more standard cycle time and helps remedy the timing problems without patchwork like heavier buffer, ect. This allows the shooter/builder to use standard Mil-Spec carbine parts, making it more reliable, easy to maintain and more predictable.

thats interesting... hadn't seen that before

[bug_eyedmonster]

I tried one of these before and did not have luck with it. There may have been other problems that contributed to the cycling issues with the AR pistol though.


Jerry

[Niviticus]

Optimal reliability/wear setups:

14.5" - Carbine
16" - Mid
18" - Mid/Intermediate
20" - Rifle

You can run different gas systems on different lengths with different results.

For example, a 16" with a Rifle gas might be a really soft shooter, but it might be sensitive vs. low power ammo.

This^^
Those are general guidelines you should follow when picking a gas system for your barrel. There are always exceptions to the rule. BCM sells a 14.5 barrel with carbine gas tube or mid length gas tube. Just know that the mid length will shoot softer and be easier on your rifle in terms of wear and tear. But the down side is that it may not cycle low powered rounds properly. I have a 16" KAC SR-15 and that upper has a proprietary gas tube that is longer than mid length but shorter than rifle length, they have it tuned perfectly to where it runs on whatever I shoot. It is also my softest shooting 16" upper I have. If you go with a gas tube that is longer it will soften recoil but may not cycle low powered rounds, you can remedy this with an adjustable gas block.

[Helius Lights]

Maybe not the most effective way but you could also adjust to a lighter buffer. Another thing to take into account is gas port size. I know spikes is one ar15 I've heard to be over gas? But I run 14.5" middy on my Noveske with no problems as of yet with all type's of 223. Dont take my word for it I'm noob I know some of the Vent's will explain better.

[cratezhayao]

There may have been other problems that contributed to the cycling issues with the AR pistol though.