ok i am wondering what is the purpose of the gas tube on the ar15?

yes i am a newbie
yes i did use the search box and came up empty
yes i am thankful for all your views

thanks all!

Quoted: ok i am wondering what is the purpose of the gas tube on the ar15? yes i am a newbie yes i did use the search box and came up empty yes i am thankful for all your views thanks all!

The gas tube is integral to the operation of the AR15.  It takes gases from a port under the front sight base and channels them back into the upper receiver, where they act on the bolt carrier to eject the spent round.

ETA: More specifically they act on the gas key, which is part of the bolt carrier.

Underneath the gas block/front sight base there is a hole drilled through the barrel to the bore.  This is called the gas port.  










When a cartrdge is fired, the expanding gases push the bullet down the barrel and as the base of the bullet pases by the gas port, some of the expanding gases are directed up through the gas port.

Directly above the gas port of the barrel, there is a corresponding port in the gas block/front sight base.  The expanding gases travel up through this port to the gas tube.





Upon reaching the gas tube, the gases are channeled into the corresponding port in the gas tube and then flow rearward through the gas tube to the upper receiver.





Inside the upper receiver the gas tube connects with the gas key of the bolt carrier and the gases drive the bolt carrier to the rear thereby cycling the action of the rifle.

nice pics MOLON...very well illustrated

It is also the week link in the AR platform.  This is by default do not get worried or stressed.  Before you can tear something else up on the gun the gas tube will glow cherry red and then begin to sag.  Once it has sagged too much the gas will be cut off and you must stop firing and get a new gas tube.  Will you ever do this?  I seriously doubt it.  This usually only occures with Full auto.  I have only once gotten one to glow, I don't care to punish my transferables.  But in case your wondering a suppressed rifle with a beta will cause it to glow!  It had been shot several times already that day, it wasn't completly cool but then again I don't walk around with a themometer either!  
Mr. Stoner was truely a genius!

The gas tube is designed to blow carbon directly into the action.

Quoted: nice pics MOLON...very well illustrated

Quoted: Quoted: nice pics MOLON...very well illustrated

+1

I read the first post, and thought "Uh oh, that poor kid's gonna wish he'd never come here."

It was nice of you to go to so much trouble.

Awesome post....very informative!   Thanks a lot!

Quoted: Quoted: Quoted: nice pics MOLON...very well illustrated +1 I read the first post, and thought "Uh oh, that poor kid's gonna wish he'd never come here." It was nice of you to go to so much trouble.

No problemo.  

Quoted: Quoted: Quoted: nice pics MOLON...very well illustrated +1 I read the first post, and thought "Uh oh, that poor kid's gonna wish he'd never come here." It was nice of you to go to so much trouble.

I thought they were gonna chew my head off but i needed to ask since i want know how it works and i did try searching for it

thank you all for the pics! i feel special

Damn Molon, those are some good pics.  Not to mention your pics on the F front sight shelf.

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