I put my 9mm AR together with a PSA Colt complete lower, PSA BCG, Faxon 8.5" barrel, and regular upper receiver. I recently tweaked my ejector to try and fix my failure to eject problem. I had loaded up a mag full of dummy rounds (hand loads) and I released the bolt to chamber a dummy round. I pulled on the charging handle to extract/eject but it was stuck. I ended up hitting the back of the buffer on the ground while pulling on the charging handle to get the bolt back. The round stuck in the chamber and I had to tap it out with a cleaning rod. The same thing happened with Hornady critical defense. I checked my hand loaded dummy rounds in my Dillion headspace gauge and they gauged fine.

The gun has less than a hundred rounds through it because of the ejection problem. Is this just a matter of break in or does it sound like the chamber is out of spec? Is this a common problem with new guns?

Remove upper from lower.
Do any rounds (factory or reloads) drop freely into the chamber, and extract easily...like by hand ??
Cause if no factory rounds or your gauged reloads rounds drop in, you need to measure/inspect the chamber.


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I'll upload some pictures with the various rounds in the chamber. I'm hoping this barrel doesn't need to be removed and sent to Faxon for a replacement.

Didn't request pics.

I asked if the factory/reloads that do pass your case gauge.....and if they can be dropped freely into the chamber, and then removed by hand.
If they go in and out....go to next step.

(Remove the firing pin out to prevent a ND)

With just the upper, load a known good round.......place charging handle and bolt into upper and gently seat the bolt by pushing it from the back.
Is it fully seated ??
If yes, draw back slowly.....is the round being pulled straight out easily by the extractor  ??
If yes....the problem may be the ejector.

If the round got stuck again...it's the chamber.


So....If the gun fails these simple tests, you need to measure the chamber.

A friend had issues with rounds sticking in the chamber of his 9mm AR and having to be mortared out which he fixed by slightly increasing his crimp.  However, it doesn't sound like that's your issue.  Since you said the bullet got stuck in the chamber it sounds like you're loading too long for that barrel so the bullet is getting pushed into the rifling when you chamber a round.  

You need to try a plunk test as 78JeepCJ mentioned with your barrel.  Take the upper off and remove bolt.  Hold the barrel muzzle down and drop one of your rounds into the chamber.  It should fall all the way in and make a plunk sound.  The round should also rotate freely.  If it doesn't drop in freely and sticks then it's probably loaded too long for that chamber and you'll need to adjust your load.

I have a Kaw Valley barrel which as I understand is made by Faxon like yours.  The chamber is ridiculously short.  I was just testing some loads and found that some bullets I have that I was planning on loading up for it will not chamber unless loaded way shorter than I would be comfortable with and for some other bullets I have I'll have to shorten my load from what I normally use with all my pistols.

Testing chamber size in a 9mm block back is different than 1911 or any locked bolt gun. First there is no extractor cut in the barrel. Which means the rounds don't seat as deep. Second the ar9 bolts surround the case head so the extractor can grip the rim. Like the 223 does. So how does one check the headspace in these guns. Take out the firing pin and extractor drop a round in the chamber and see if the bolt closes and makes contact with face of the barrel. If it does not, drop in a sized empty case and check again. If it closes now then bullet maybe seated too far out. Or the throat is too small. If bolt doesn't close then case is too long check or chamber too short. Another problem could be too deep of a chamber, which cause the cases to headspace off the extractor which causes them to break.

Failure to extract could be an oversized chamber or you taper crimped your ammo two much. Try factory ammo and also try steel case and aluminum cased. If factory ammo sticks bad chamber.

We are having to relearn what the WWII guys figured out about blow back sub guns

I need to compliment you. I don't own anything Faxon but I am looking for parts to buy from you because you are CONSTANTLY on these boards giving feedback and advice which says a lot about you and your company. There is only one other company that I see here on a consistent basis and that is Macon Armory.  I have all parts accumulated for my first AR build however, there will be others and I will incorporate as many Faxon parts as I can in that build. I can imagine that most feedback you get is negative so I figured I would toss you some positive feedback.

Ran into the extraction problem with some barrels from NFA. Upon inspection of the chamber the headspace is good, but there is very little lead or freebore in the chamber. In other words the rifling starts too soon. So the bullets locks into the rifling. So the drop a round in the chamber and it should go clunk and spin freely is a good test.  I'm going to use a Clymer 9mm finish reamer which has a long lead/freebore and recut the chamber.