# AR15 Question



## Paulk (Dec 15, 2007)

I just recently put a different upper on my ar, but now i am noticing that the bolt carrier doesn't click into the upper like it did on my previous upper. So i was wondering if it should click into the upper. Any help is appreciated.


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## darkgael (Feb 10, 2006)

Not exactly sure what you mean by "click" into the upper. Do you mean that it doesn't go into battery? Something else?
Have you checked the headspace in the second upper?
Bottom line, though, is that it should work exactly the same in both.
Pete


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## Paulk (Dec 15, 2007)

Well when i put the bolt carrier into my old upper and i tried to pull it out with out charging handle it would just stay in, but now on my new upper you can pull it out a little bit. Oh and I haven't check the head space yet.
thanks


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## darkgael (Feb 10, 2006)

Sounds like it's not going completely into battery. When you have closed the bolt, It should not move. Have you tried this with an empty case inserted? Did it still move? 
Check the head space.
Pete


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## Paulk (Dec 15, 2007)

I just tried putting a snap cap in and the bolt carrier still moved back when I pulled on it. So I will have to go buy a head spacing gauge.


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## Paulk (Dec 15, 2007)

What do you think might be stopping it from going all the way into the battery?


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## darkgael (Feb 10, 2006)

Basically, it could be that the parts just don't fit together. The tolerances are quite tight. If one is a little off, your gun won't work. Frequently, uppers require some work to headspace properly. The original bolt/upper combo was fitted together. 
If you have a headspace issue, if, it is most probably fixable.
Gauges - the gauge will tell you if the headspace is correct.
Pete


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## The Norseman (Jan 8, 2005)

Morning AR Enthusiasts,

Say, out of curiosity.....what does the BCG Gas Key look like?
What does the Gas tube coming into the receiver look like?
What Diameters?

Also, I go to AR15 dot com alot and read through their stuff.
I believe they also got Army Tech Manuals on there for your
viewing. They are excellent for trouble shooting problems.


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## Aznative (Apr 6, 2009)

Here is a pic of the bolt carrier key/gas key. The gas blows into this pickup tube to disengage the locking lugs.
http://www.armalite.com/ItemForm.aspx?i ... 0a2a71510d
Here is a pic of how it fits on the BCG.
http://www.armalite.com/catitem2.aspx?C ... 0a2a71510d
Here is a pic of the barrel assembly. The gas tube is the long thin tube above the barrel.
http://www.armalite.com/catitem2.aspx?C ... b0673837cb
The gas tube extends thru the front of the receiver. Make sure weapon is unloaded. Cock weapon. Push rear pin out and tilt upper receiver. remove BCG and charging handle. With a flashlight look into the area the BCG slides. Look to the front of the upper receiver and you will see the rear of the gas tube. The rear of the gas tube matches up with the front of the gas key. This is how the hot gas gets into the bolt to start extraction.


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## striped1 (Aug 17, 2005)

try a new bcg. it is better not to switch bolts between uppers.

could be a gas key issue loose and in need of torquing and staking.


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## Paulk (Dec 15, 2007)

Thanks everyone, I finally got it fixed.


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## Aznative (Apr 6, 2009)

Paulk said:


> Thanks everyone, I finally got it fixed.


Well please tell us what fixed it.
Thanks


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## Paulk (Dec 15, 2007)

I got a buddy of mine to help me. So I just gave it to him to fix. He said it was something to do with the gas key.


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