What Length Gas System...?

[JCV]

Thinking of building my gf an AR.
Magpul's fixed carbine stock looks appealing, she hates my rifle length stock.

Would there be an issue using a mid-length gas system with this?
I swear I've read on here that the length of the gas system must agree with the buffer tube length?
What are some combinations that don't work?

 

[Another_David]

Not a problem.

Maybe you're thinking about the different buffer length tubes: carbine and standard rifle buttstock length? But you can run a carbine stock on a rifle barrel/gas tube and the reverse works fine too.

Where things get quirky is with the different combination of gas tubes and barrel lengths, which sometimes you do want to change buffer weights depending on your front setup.

Thoroughly confused yet?

 

[atilla]

all you need is a standard buffer, don't get a heavy one.

tube's the same, that's based on the stock, not the gas system.

 

[PaulD]

Based on what I learned when I built mine, the longer the gas system the better. It affects the timing, cyclic rate and pressures. If you go with a longer gas system you'll lessen the need for things like a heavier buffer, full auto bolt carrier, etc. This means it will be nicer to shoot and be more reliable.

So if you go with a 16" barrel, go mid length. If you go with an 18" barrel, go rifle length.

I'm no expert though so I could be wrong.

 

[JCV]

Thanks guys.
My questions are answered.

Am I confused? Sure. As "simple" as they are to build, there's much more to them.

Carbine Stock, standard buffer, mid length gas system - not a problem.

 

[beaker]

It works fine. I have a fixed magpul MOE stock with a rifle buffer and middy gas system and it works great. Middy rules for mid length barrels!

Thinking of building my gf an AR.
Magpul's fixed carbine stock looks appealing, she hates my rifle length stock.

Would there be an issue using a mid-length gas system with this?
I swear I've read on here that the length of the gas system must agree with the buffer tube length?
What are some combinations that don't work?

Sent from my Galaxy Nexus using Tapatalk 2

 

[Another_David]

Thanks guys.
My questions are answered.

Am I confused? Sure. As "simple" as they are to build, there's much more to them.

Carbine Stock, standard buffer, mid length gas system - not a problem.

right, regardless of what you're building, having all the right pieces that fit together is about 50% of the project, lol!

so just to be clear, there are four major components in the stock: the stock itself, the buffer tube, the buffer, and the spring. Pick your stock then determine which you need: carbine or standard length tube, buffer and spring.

And if you're still confused buy it as a kit

http://www.pkfirearms.com/Magpul_Fixed_Stocks/228/c

EDIT: should also mention there are milspec and carbine versions of the buffer tube. milspec typically works with everything but YMMV

 

[colt_fan]

Thanks guys.
My questions are answered.

Am I confused? Sure. As "simple" as they are to build, there's much more to them.

Carbine Stock, standard buffer, mid length gas system - not a problem.

Try building an AK! You need to have the correct receiver style for the different kits available!

Sent from my SGH-T999 using Tapatalk 2

 

[JCV]

right, regardless of what you're building, having all the right pieces that fit together is about 50% of the project, lol!

so just to be clear, there are four major components in the stock: the stock itself, the buffer tube, the buffer, and the spring. Pick your stock then determine which you need: carbine or standard length tube, buffer and spring.

And if you're still confused buy it as a kit

PK Firearms | Online Store

EDIT: should also mention there are milspec and carbine versions of the buffer tube. milspec typically works with everything but YMMV

thanks for the link!

Try building an AK! You need to have the correct receiver style for the different kits available!

Sent from my SGH-T999 using Tapatalk 2

lol AK's seem like too much work, i'm not there yet.

 

[colt_fan]

lol AK's seem like too much work, i'm not there yet.

a lot more fun to build though, you actually have to think about stuff. otherwise you end up like me with a receiver that does not match a build kit, with the wrong package of rivets. to add insult to the injury, i thought i was getting a deal and bought multiples! so now instead of 1 receiver, 1 build kit and 1 set of rivets, mine is x3! but it's now an excuse for me to own 6 AKs...

 

[JCV]

hahaha which is not a bad thing at all!

 

[Another_David]

Based on what I learned when I built mine, the longer the gas system the better. It affects the timing, cyclic rate and pressures. If you go with a longer gas system you'll lessen the need for things like a heavier buffer, full auto bolt carrier, etc. This means it will be nicer to shoot and be more reliable.

So if you go with a 16" barrel, go mid length. If you go with an 18" barrel, go rifle length.

I'm no expert though so I could be wrong.

whoa there compadre

not so much

there is a great thread somewhere on NES that links to a full analysis of how the barrel and gas tube length affects the gas tube pressure but I can't find it at the moment.

 

[Coyote33]

A 20" barrel is not really all that long, considering so many hunting rifles are like 24", and shotguns are 28".

That said, you can also get a S&W all done, for just over $600, ready to go, no guesswork.

Good luck, and let us know what you do, and how you arrived at your decision.

 

[NHCraigT]

IMHO - Midlength with proper corresponding system parts.

 

[warwickben]

Just don't pin your gas tube on upside down this time

 

[JCV]

i'll try

 

[PaulD]

whoa there compadre

not so much

there is a great thread somewhere on NES that links to a full analysis of how the barrel and gas tube length affects the gas tube pressure but I can't find it at the moment.

Ok, so I'm wrong but you can't say why? I'm happy to have more information if you can provide it.

 

[Another_David]

Ok, so I'm wrong but you can't say why? I'm happy to have more information if you can provide it.

see dwell time at the bottom

AR15BARRELS.COM - Randall's description of AR gas operation and how everything works in harmony

Optimum dwell time is right around 0.200 ms when you use the two most common gas system/barrel length configurations of 20" rifles and 14.5" carbines.

 

[PaulD]

see dwell time at the bottom

AR15BARRELS.COM - Randall's description of AR gas operation and how everything works in harmony

Thanks. I'll read through it.