(ADVICE NEEDED) 10.5 Norc Upper Issue

Battle Pug

Battle Pug

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So, took my new 10.5 Norc Upper (on an Armalite lower) to the range this weekend.

Issue:

It would only fire 1 x round (MFS 55gr FMJ), then STOPPAGE.

Partial bolt fwd or a bolt fully fwd. Even had a couple partial feeds, but always after one round fired.

I am thinking it is a Buffer and spring issue. The issue being the buffer is from an 14.5 AR, and not heavy enough to support the reduced gas exchange on the 10.5.

Any insight or advice is much appreciated.

I have already ordered an H2 carbine buffer and springs to try and remedy the problem...
 
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what do ur rounds look like after the stoppage, u might have a problem with ur upper and lower being too far apart.
 
Your logic is backwards, OP.

Under gassed so you install a HEAVIER buffer? That would exacerbate the problem.

If it is sometimes not even cycling far enough to pick up the next round in the magazine (empty chamber, but fully seated mag), then it is under gassed.

Try a lighter buffer/weaker spring if you have one. Or full powered ammo. MFS is a bit on the weaker side.
 
That's the big nut that screws down on the buffer tube. It has little notches in it (hence "castle nut") so once tightened, it can be staked in place with a punch.

If it's loose you can get weak cycling.

castle%20nut%20staking%201028%20WEVO.jpg
 
I did some research and I came up with the following:
-change the extractor spring to an extra power extractor spring from Wolff
-heavier buffer (buffer spring and buffer?)
-full auto bolt assembly
-1/8" plumbing o ring over the extractor spring (forget the other name for this mod)
 
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Battle Pug said:
Suppose the gas port would be an armourer only fix?
Click to expand...

Did you check the castle nut? Can you turn it with your hand? Is it staked properly? How does the buffer tube mate with the spring plunger? Do you have a pic? Kevin B may be right about the gas port size, but I would be checking the obvious stuff first before sending it off. You could also try different ammo as TSE pointed out.

It's possible your carrier key could be loose as well. Do you have a pic of the carrier and key? I thought that the Norcs came with FA bolt carrier...I could be mistaken, but if so, you could eliminate that from the issues....

The carrier key sits on top of the bolt carrier. It looks like this:
180977_10150107267308699_595683698_6174576_6775929_n.jpg
 
The way I like to fix an undersized gas port is to shoot it until it opens up to normal sizes.

EDIT - Yes, I am kidding. /sarcasm tag

But seriously, looks like a gas issue.
 
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Stop. full stop.

When you said the bolt is fully forwards, does it strip a round?

Is the stoppage a failure to strip a round and deliver the round to the chamber? Or is it a failure to extract the spent casing from the chamber or just ejecting the spent casing?
 
It would fire a round...click. Nothing, cant and look...bolt fully fwd.

I'd tap and rack.

Bang...then nothing. This time a round would be partially fed creating a stoppage.

Bolt cocked and locked to the rear, remove mag, remove stoppage, reload, fire.

same thing..maybe this time the bolt would not be fully forward...

My buddy and I figured it is a gas issue.

He had a similiar prblem with a 11.5 factory, bought a h2 buffer and spring and has never looked back.

Appreciate all the help guys.
 
Looks like you have an undergas situation or there are "drags" in the system.

Your MFS Russian made ammo could be on the weak side as well which may not have enough pressure to actuate the system.

Try some other ammo - such as American made winchester .223 or AE .223. Also, try some other magazines such as Pmag or GI mags to make sure it is not that the magazine which is dragging the bolt carrier. Put your buddy's bolt carrier group into your rifle to see if it is the BGC that is out of spec.

Your situation has nothing to do with buffer weight or extractor spring.

If trying all the above and it still won't work- it should go back to the factory for warranty repair.
 
I had an issue similar to this, although I was running a 14.5 with a muzzle brake. Firearm was over gassed, and extracting way to hard inducing malfunction issues. My issue was "overgas" and switched to a H2 Buffer. Runs like a dream.

If your undergas and need a light buffer, I have a Questar buffer that is lighter than average if you want to give it a go.
 
Try everything else first (buffer, castle nut etc) before you go the 'openning up the gas port' route. I had short stroking problems on a 10.5" barrel once. If you know someone who has a recoil booster (Dlask, PWS) try that . It sure helped mine. If you do the openning up the gas port use wire gauge drills and go up a thou at a time. If you over gas it the brass will chase the bullet downrange and you'll knock the lower apart over time.
 
Do not open gas port on you own - it should not be your responsibility to deal with gas port issue. Your responsibilty as a user is the use of proper good quality ammunition and good quality magazines. It stops right there and go no further. Any funky fixes will void your warranty.

A properly designed and manufacturered AR does not need those "boosters" If you need some funky muzzle devices to make it work, your carbine is a lemon.
 
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