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Posted: 11/11/2012 3:07:50 PM EDT
My 7.62x39 upper will chamber rounds about 75% of the time.  The other 25% the extractor will not go over the case rim of the chambered round.  I have been fighting this issue for days thinking it was a chamber problem, because it seemed to not go into battery.  Is this common?
It is an AR15 Performance BCG.  Have a look at my bolt face, looks like the extractor is way tight:

Link Posted: 11/11/2012 7:09:59 PM EDT
Link Posted: 11/11/2012 9:40:04 PM EDT
Good eye.  Comparing with other extractors it does seem to lack a bevel.  I'll pull the extractor off my CMT bolt while I wait for an answer from AR15 Performance.  
Having a look at the Prvi Partizan brass which is the only stuff that was close to 100%, I notice it has more of a rounded edge on the rim bottom.  Must have been that tiny difference enough to make it work.
Has anyone seen an extractor like this before.  My experience is pretty limited.
Link Posted: 11/12/2012 6:12:17 PM EDT
Link Posted: 11/12/2012 6:45:57 PM EDT
[Last Edit: 11/12/2012 6:49:38 PM EDT by hawk78]
Originally Posted By sully:
When the rifle is having a hard time getting the extractor around the lip of the case, is this upon manual cycling/loading, or during firing?  Also you state that it runs better on the Privi, have you tried any other brass cased ammunition, or is most of the problem on steel cased ammunition?

CY6
Greg Sullivan "Sully"
SLR15 Rifles
TheDefensiveEdge.com
(763) 712-0123


It's all the time, all ammo.  I always loaded from the mag, and it was both using the bolt release and using the charging handle.  If I could get the extractor over that first round, then the chances were better the next would fire, but not 100%.  For sure the increased force of the carrier slamming forward when actually shooting helped.  I shot Brown Bear, Hornady steel case, Federal brass, Remington brass (the most trouble of them all), and Prvi Partizan.  
There are a few cases I have where the extractor got about halfway over the rim, and when I pulled back the charging handle it tore through the rim partway.  This was only the Remington and Hornady steel case.  
When inspecting the cases, I noticed the Prvi has a easily distinguishable rounding or bevel on the bottom edge of the rim, which is why I believe it to be the least problematic letting the extractor actually get over the rim.  

What did have me worried were the couple times I got the dreaded 'click' when pulling the trigger, and after getting the loaded round out noticing an indent on the primer.  This happened during the times when the extractor was about halfway on the rim, but not enough to actually pull the round out.  I did contemplate that with the extra firing pin protrusion which is supposed to help the 7.62x39 run, I could end up with a OOB kaboom with it.  Am I wrong on that?  I hope so, being a lefty and really riding the charging handle with my cheek, that could be a bad time.
 
I have a spare extractor I will be trying later tonight when I get a moment.  After talking with a local gunsmith who has built a ton of AR's, he said he's seen an out of spec extractor that looked like this one. Mind you he hasn't actually seen it, just the way I described it over the phone.  He suspects it machined too narrow, permitting it to encroach too close to the firing pin.  It also doesn't have a nice bevel like stated before.  Maybe one caused the other, due to the way they are machined???

I can post extractor comparison pics when I have them both out if that might help anybody out, or for future reference to anything like this.



 

Link Posted: 11/13/2012 5:17:43 AM EDT
[Last Edit: 11/13/2012 5:18:59 AM EDT by hawk78]
I swapped extractors with my spare bolt.  ARP bolt on the left, CMT bolt on the right.  The extractors are visually identical minus the bevel, although the 'bad' extractor in question had about twice the spring pressure, and a longer black plastic insert inside the spring (forgive my terminology).  Still appears to sit too far in, but looks better than before.  Do I send this bolt back or is it acceptable for this extractor to be this far in toward the firing pin?



Link Posted: 11/13/2012 10:30:30 AM EDT
Get a 7.62x39 extractor.
Link Posted: 11/22/2012 1:53:05 PM EDT
So the extractor on the AR Performance 7.62x39 bolt AND the CMT 7.62x39 bolt are NOT 7.62x39 extractors?  These are both factory BCG's, not pieced together units.  I am at a loss.  If I was given 5.56 extractors I would be pretty upset.  The only thing I did was swap extractors between bolts.

Should this extractor being so far in towards the firing pin be a concern?
Any more info needed?  Should I return the BCG to AR Performance?
Do I have a 5.56 extractor?  
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