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n2ipsc

Ar-15 Extractor Tension

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n2ipsc   

Looking for a voice(s) of experience setting up AR extractor springs/inserts...

Have been battling a weird failure-to-extract/feed jam problem with a CAR. The bolt strips the next round out of the magazine and (partially) into the chamber, but the preceding empty jams the bolt, protruding out of the port at right angles in a somewhat obscene parody of a one-finger salute (or maybe it's just the obscene thoughts that come to mind whenever it happens). Usually, the base of the case is jammed and the open mouth of the case protrudes, but the occasional empty will jam mouth-first into the port with its base sticking out (!).

Changed two things on the gun - 1) replaced the collapsible, carbine-length buttstock with a standard-length SOCOM (incl. the rifle-length spring and rifle buffer - I've got really long arms and, even fully extended with a 1" pad, the collapsible stock was too short for my liking), and, 2) replaced the stock extractor spring with a Wolff +10% and D-fender D-ring.

Am thinking one or both of two things are going on -

1) Some weird combination of higher port pressure from the shorter barrel, coupled with the longer spring, and/or...

2) Too much extractor tension, e.g. the empties coming forward with the bolt having failed to eject.

Removing the D-ring didn't solve the problem. Naturally, I've no idea where I put the stock spring and blue polymer insert (cut one coil off the Wolff and lost the D-ring, haven't had a chance to test yet). The gun ran flawlessly with the original carbine stock & buffer, and a stock extractor spring with a blue polymer (factory?) insert...

Am about to the point of junking the front sight for a JP adjustable gas block, but before plowing any more dinero into this barfing POS, thought I'd seek out the wisdom of those who have gone before...

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BLUE inserts go with rifle-length gas systems. BLACK inserts go with carbines. Get a BLACK insert and spring for your CAR. Go back to stock configuration spring and insert and see what happens. Got a spare extractor? One should be in every spares kit.

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kurtm   

Check your ejector. It shold be hard to depress and should move freely. A drop of oil here occasionally also helps. I do mean the EJECTOR not extractor.

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Paule   

Kurt is right, most likely cause is something making the ejector stick. Brass shavings are the most common culprit.

As to the inserts for the extractors, the colors are only to identify which spring is which. The durometer of the inserts themselves is the same. Very unlikely that you have too much extractor tension. The ejector spring, unless the plunger gets stuck, is way stronger than the holding power of the strongest extractor spring. Extractor tension being too light is a far more common problem, hence the D-ring, o-ring solutions that are common.

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Platinum   

I recently had a failure to eject as you describe and found out it was the ejector - the spring was broken into four pieces.

Like the last two guys said - check the ejector.

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n2ipsc   

Thanks, all, pulled the ejector, no visual problems, but replaced the spring with new and will give it a go...

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I've occasionally encountered a really weird problem, one that duplicates your conditions. (Only one of several, however.)

A combination of a sharp-edged ejector plunger and ejector hole, combined with slighlty soft brass. the brass shaves off and build sup int eh ejector tunnel. The ejector binds, and fails the eject. What makes it a bear to figure out is that the ejector periodically spits this gunk out. So you can have a malf, shoot some more, have another, and then look, and if the ejector has blown the chips out, you don't see anything.

Stone the ejector edge, and check your ammo. The main culprit is some lots of WW white box.

If not that, there are about four other things to check, but the previous advice of going back to stock parts and seeing how it works is good.

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n2ipsc   
I've occasionally encountered a really weird problem, one that duplicates your conditions. (Only one of several, however.)

A combination of a sharp-edged ejector plunger and ejector hole, combined with slighlty soft brass. the brass shaves off and build sup int eh ejector tunnel. The ejector binds, and fails the eject. What makes it a bear to figure out is that the ejector periodically spits this gunk out. So you can have a malf, shoot some more, have another, and then look, and if the ejector has blown the chips out, you don't see anything.

Stone the ejector edge, and check your ammo. The main culprit is some lots of WW white box.

If not that, there are about four other things to check, but the previous advice of going back to stock parts and seeing how it works is good.

Aaaah, many thanks - describes the problem precisely. Thought I had it wrung out at 400+ barf-free rounds in practice - and you know the rest - next time my toy figured out it was at a match - started afresh.

Off to the bench to disassemble the bolt again... :P

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Not to insult, but make sure your gas rings are not lined up. With a round only halfway ejected and picking up another round, sometimes its a gas problem.

The ejector and extractor should be hard to move with your nail. If they become very easy to depress, its time to replace them.

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The official armorers test for gas rings is to pull the bolt forward and stand the bolt/carrier assembly on the bolt. If the weight of the carrier collapses the bolt, there isn't enough friciton. If it stands up, there is enough.

If it is short-stroking, the problem I've found more often than others is a loose carrier key. Back in the old days they never came loose. Now, we see one or two a class that comes loose.

After staking keys with this-or-that method for a couple of decades, I've now adopted the Ned Christiansen MOACKS. (Mother of all carrier key stakers.) Yes it is expensive, but if you need more than a couple ever re-staked, it is money well-spent.

Let us know what you find.

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cking   

Everything everybody has mentioned is true. Also check wear on gas tube. Sounds like the rifle has got some rounds through it. If the gas tube wasn't lined up when new, they can wear on top edge and its real hard to see that spot.

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ditto, what cking said, it sounds like a problem i had, with mine that was very aggravating, and hard to diagnose. it turned out to be gas blow by from the gas block, it was aluminum and when it heated up gas moved past it, i replaced the block with a steel one and have had no problems since. even if your block is steel, now....it could still be worn out.

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gotm4   

I too think that your problem lies in you ejector not pushing the casings hard enough to clear the ejection port. It's really hard to have 'too much' extractor tension. In my 11.5" SBR I have the Wolff XP extractor spring combined with the D-Fender ring. I run a Enidine hydraulic buffer and this causes the extractor to hang onto the brass for so long that the rifle ejects forward between 1 and 2 o'clock forward instead of the typical 4-5 o'clock behind you ejection.

If I were you I'd just replace the ejector, and ejector spring (use a chrome silicon one). You can get both from Brownells. For good measure I like basically rebuilding the entire bolt, ring, extractor, extractor spring and checking the gas key and restaking if needed. I think it's best to replace them as a set so that they wear together at the same rates.

It is possible to have too much ejector tension where it'll cause the extractor to release the casings too early which causes an empty and a loaded round to jam up in the upper receiver as well but this isn't your problem.

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There could be many root causes of your ejection problem. Here are the ones that spring immediately to mind:

1) Insufficient gas (bolt carrier not cycling fully). Test for this by loading one round in a mag, loading it, and firing; if you have insufficient gas, the action will not reliably lock open on the empty mag. Insufficient gas is usually caused by a gas leak somewhere - at a loose carrier key for example.

2) Too much gas (bolt carrier cycling too fast). This is a common problem with carbine gas systems due to the gas port being located at the point of peak pressure. A previously reliable rifle can suddenly become unreliable as the gas port erodes and gets bigger (i.e. more gas). This is tough to diagnose, but is sometimes betrayed by an excessively forward (12:30-13:00) ejection pattern. If a heavier buffer cures the problem, then this confirm the overgassed diagnosis.

3) Bad ejector/spring. As others have said, the ejector can malfunction due to fouling (brass shavings) or a bad spring. Squirt some CLP on it and work in and out to ensure robust operation.

4) Bad extractor/spring. Use the proper insert wsith the Wolff spring - no need for the D-Ring IMHO.

5) Crap ammo. If you are using Wolf (or have used it before) - STOP ! Same with reloads, including commercial reloads, and surplus (even XM193). Run some brass commercial ammo, like WWB or American Eagle, during troubleshooting.

I also suggest looking at the AR15.COM troubleshooting forum. Good, luck.

Edited by StealthyBlagga

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n2ipsc   

I am constantly reminded of why I so like this forum.

After countless battles, it turns out that this all apparently came down to the dreaded McFarland gas ring/sticking bolt problem, as detailed HERE and elsewhere. As I was reminded - sometimes an "improvement" - isn't. <_<

Many thanks to all who took the time to offer assistance and insights! Maybe I'll hang onto this puppy after all...

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