New Build, Extraction Problems-Fix on Post #23

[koden]

If it locks back on an empty mag your not undergassed.

Can you post a pic of the jam and how the brass looks once it comes out of the gun after being fired?

If you are overgassed the BCG could be trying to extract too soon and the case has not contracted enough to allow removal. Remedies are heavier buffer and or spring and adjustable gas block.

Seeing pics of the spent brass will tell us a lot.

[Igor Kross]

I'm low on ammo at the moment, I think I have six rounds or so left. My BCM extractor kit should be here Mon or Tues, after I install it I'll see if any of those rounds malfunction, and take a picture if it does.
As far as the brass goes, all of the empties have a large dent in the case neck where they were jammed up against the locking lugs after they failed to eject. Most of the other brass have dents on them where the bolt smashed into them when they couldn't feed (because of the spent shell in the way). I'll take a picture and post those too.
In the meantime, after doing some research online, a lot of people reference a small rubber insert that's supposed to be inside the extractor spring. I believe one comes with the BCM kit as well.
Mine has no insert in the extractor spring, just the spring. Could that be causing a problem?

[nocoolname]

With my similar problem, would you guys rather me make my own thread, as I'm not sure if the OP's fix will work for mine after taking my bolt apart this evening.

[rabiddawg]

If it locks back on an empty mag your not undergassed. .

Depends what it is locking back on. It could be locking back on the magazine follower, which is still short of the bolt catch.

[Igor Kross]

I was looking around on youtube today and this video:

https://www.youtube.com/watch?v=kYm5UjojDMU

at 2:02 *seems* to be exactly what's going on with my rifle.

[LRRPF52]

I'm low on ammo at the moment, I think I have six rounds or so left. My BCM extractor kit should be here Mon or Tues, after I install it I'll see if any of those rounds malfunction, and take a picture if it does.
As far as the brass goes, all of the empties have a large dent in the case neck where they were jammed up against the locking lugs after they failed to eject. Most of the other brass have dents on them where the bolt smashed into them when they couldn't feed (because of the spent shell in the way). I'll take a picture and post those too.
In the meantime, after doing some research online, a lot of people reference a small rubber insert that's supposed to be inside the extractor spring. I believe one comes with the BCM kit as well.
Mine has no insert in the extractor spring, just the spring. Could that be causing a problem?

Yes, that could, and might the culprit here if your malfunction looks like the Vuurwapen blog video at 2:02.

That kind of malf can be caused by:

Weak extractor spring or missing insert
Too early extraction, where the case is still obturated in the chamber
Chamber with imperfections and tool marks that don't allow primary extraction

[Igor Kross]

Thanks LRRPF52.
My BCM spring should be here today according to tracking.
I'll put my remaining few rounds through and see what happens, but I suspect the true test won't be until I can afford a few more full boxes to put through it. I'll update when I can.

[Igor Kross]

I received and installed my BCM spring and insert (no o-ring), and test fired the rifle.
The first round produced a dense white cloud of smoke out of the ejection port.
I didn't hear or feel anything abnormal.
I cleared the weapon and inspected it, and didn't notice anything unusual.
I also retrieved the brass and didn't see any signs of damage.
I attributed this to the rifle venting excess CLP, but I can't help but wonder if maybe it's extracting too early.
Any thoughts on this?

After that I fired the other five rounds and all fed and extracted just fine.
No other clouds of smoke.
The rifle tossed the brass at about 3 o'clock, 10 feet away.

I'm going to order 100 rounds of Wolf and see how the rifle digests it.

Thanks again everyone.

[LRRPF52]

The first round smoke is from lube in the BCG, especially on the bolt tail. If there is any lube in the chamber, you can see that too, but you really want to have your chamber clean and dry for a number of safety reasons.

[Igor Kross]

OK thanks LRRPF52.

When it happened I was thinking "Oh great, here we go again."

I'll make double sure the chamber's dry from now on.

[SG4247]

The o-ring is not needed unless the extractor spring is not quite up to snuff. If you can move the extractor with your fingers, its just not going to be reliable in Grendel.

I carry some spare o-rings and extractors/springs with me to the range. I have broken two extractors during competition now in the last three years (different guns). One failure (this year) will cost me a championship.

A fresh spring will often do the trick. Once the spring gets some cycles on it, the problem may re-manifest itself. Installation of the o-ring (or D ring on some factory guns/bolts) really extends the springs life significantly.

[Igor Kross]

Hi SG,

Sorry to hear about your misfortune with the extractor failure costing you a championship.

Do you have a particular brand of extractor or spring that you favor?

The BCM spring seems to be working just fine for now without the o-ring.
I *can* move it a bit with my finger, but nowhere near as much as I could with the stock spring.
I'll keep an eye on the extractor tension and add the ring if it seems like it's getting loose.

Good luck next year!

[LRRPF52]

The o-ring is not needed unless the extractor spring is not quite up to snuff. If you can move the extractor with your fingers, its just not going to be reliable in Grendel.

I carry some spare o-rings and extractors/springs with me to the range. I have broken two extractors during competition now in the last three years (different guns). One failure (this year) will cost me a championship.

A fresh spring will often do the trick. Once the spring gets some cycles on it, the problem may re-manifest itself. Installation of the o-ring (or D ring on some factory guns/bolts) really extends the springs life significantly.

Was that a DPMS LR-308 extractor by any chance on one of the 6.5's?

[SG4247]

Was that a DPMS LR-308 extractor by any chance on one of the 6.5's?

Yes,

Failures for me so far:

1. Extractor sheared claw - DPMS .308 AR-10 (shooting the 6.5 x 47 Lapua cartridge).
2. Extractor sheared claw - Les Baer 264 LBC with only 400 rounds of 30.5 CFE and 120 bullet.
3. Bolt - Alexander Arms 6.5 Grendel - cracked both lugs adjacent to the extractor. Roughly 1000 rounds on bolt. Terrible accuracy until it was replaced with a JP 6.5 Grendel Supermatch bolt, then accuracy was restored.

No failures yet with Armalite, JP, Maximum, or Underground Tactical factory direct AR bolts or bolt components. (knock on wood!)

[Igor Kross]

So the issue wasn't fixed by the BCM spring. I've installed the o-ring on the extractor and I'm going to test fire it here in bit, after I clean up the copper shavings from around the locking lugs.
If it persists I guess I'm sending it back to Radical.
Thanks for all the suggestions everybody.