16'' extraction problem

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clovis

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Hi,
I am trying to figure out a problem I have with a 16'' (short handguard). It has been built with a A1 fixed stock. It will extract one over 3. When it extract correctly, it feed with no problem. But if it doesn't it will still strip a round from the mag and jam. I am trying to figure out why it is not extracting correctly. I tought that with a rifle buffer and spring it should work ok. Any help or advice is welcome.
Thanks,
Clovis
 
Where does the empty casing end up if it doesn't extract (fully in chamber, half out, etc.)? What position is jammed cartridge in?
 
The empty case is still in the chamber. I have already checked the chamber and it is nice and shinny.

Clovis
 
It does it less often with reload than factory. reload are milder.

The bolt ring are not align. The extractor looks OK but I can see on the empty brass that it jumped over the rim.

The extracot spring is new and the small rubber is in it. But still the extractor is a bit easy to move with a finger compare to the extractor of an AK or a mini 14. I feel the pressure in the chamber is still high when the bolt start to extract the empty shell.

Clovis
 
When you are clearing the jam, does the empty case extract easily from the chamber? Or do you need to use a cleaning rod to knock it out?

If it extracts easily, then the problem is that your rifle is unlocking too early, while the case is still stuck to the chamber walls. This would be very strange on a 16" barrel with a rifle buffer. The only thing I can think that would cause it is an oversize gas port.

If the case is still stuck when you go to clear the jam, then the chamber or brass is rough or otherwise defective, and the brass is not releasing as the pressure drops.
 
To remove the shell from the chamber I just need to cycle the action by hand. The brass goes out very easy.

The bolt is a Bushmaster. Is there problem with this specific bolt brand?

What size the diameter of barrel port it is supposed to be on a 16"?

Clovis
 
I belive it is Bushmaster. I am getting this upper from someone so I am not fully sure. It might be also olympic.
 
I have often run into bushmaster bolts that have week extractor springs. They often fail to extract with barrels shorter than 20" until replaced with heavy/stronger springs then they work fine.
 
I had the same problem with my 16" build. Try using a heavier buffer. Eg if you are using a carbine buffer, try an H buffer. This is one of many possible remedies.
 
I think it is not short stroking because if the mag is empty, the bolt is going to stay open locked by the latch. But the empty case will still be in the chamber.

After reading all your comments, Ithink it is either a bad extractor spring or the extraction is started too soon and there is still too much pressure in the shell to extract it from the chamber.

The extractor fix should be simple. I may just order the wolff HD and may be the o-ring. But if it is a timing problem, how can I slow down the extraction process. I have a rifle stock with a rifle buffer and a riffle spring. I know it exist heavier buffer for the telescopic stock but is there any for the rifle??

Thanks,
Clovis
 
clovis said:
I think it is not short stroking because if the mag is empty, the bolt is going to stay open locked by the latch. But the empty case will still be in the chamber.

After reading all your comments, Ithink it is either a bad extractor spring or the extraction is started too soon and there is still too much pressure in the shell to extract it from the chamber.
Click to expand...

It sounds to me like you understand the functioning of the rifle well enough to solve the issue yourself, eventually.

You can try changing your extractor, since it is cheap and easy to do, but (and I think you already realize this), all the evidence is suggesting your extractor works just fine. You're deforming the rims of your cases trying to pull them out under pressure, fer chrissakes.

The gas port is supposed to be 0.063" on a 16" barrel. There is a guy over on AR-15 who found last week that his factory Colt 16" has been drilled too large, so it is not unheard of. A stronger recoil spring might also help slow down the unlocking. If not, you may have to go to a pigtail gas tube to get some extra dwell time.
 
LOLLL Someone is a friend of my friend. I saw the guy few times at the range. He wanted to sell this upper for $300 because he had problem with it. He bought it about 15 years ago and did not used it a lot because of the malfunction. There is nothing stamp on it and he think it is a bushmaster. He remember that he bought it from Atlantic ordonance. If I can fix it, it is going to be a good deal. I intend to replace the A1 upper by a new Flat top. I am in AR myself for about 4 years. I can understand how it work and I bought some tool for it but I don't have much experience with troubleshooting of it because all people I know that own an AR have no problem with it. So that is why I am asking so many question. And by the way your help is really appreciated.

Clovis
 
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