Extractor marks on cases an issue?

[Pistoler0]

My new 7.62x39 AR is leaving some extractor marks on the cases, could this be an issue?

I did put a BCM extra power extractor spring in it following the advice on the interwebs.

This is how they look:

I have only put 40 rds through it so far, I am thinking I should check again after 200 rds or so.

Any thoughts?

 

[Shadow9mm]

Hard to tell from the pics. Need a pic of just the head. If your talking about the marks on the side of the rim of the casing those are from the extractor grabbing the casing. The ejector marks would be in the headstamp area opposite the extractor marks. Also your primers look fine, round edges, not flowed, no cratering. Thinking you may have gotten extractor and ejector marks mixed up....

Also, I don't change parts on guns, until I have shot my gun and believe it to be an issue with my specific weapon. You could very well end up causing a problem where there was not one before.

 

[Pistoler0]

If your talking about the marks on the side of the rim of the casing those are from the extractor grabbing the casing. The ejector marks would be in the headstamp area opposite the extractor marks. Also your primers look fine, round edges, not flowed, no cratering. Thinking you may have gotten extractor and ejector marks mixed up....

Shadow,

yep you are right, I mixed in a post about ejectors instead of extractors. I deleted it.

But yes, I was referring to the marks on the side of the rim casing. Those are the extractor marks right? Are those normal or are they a cause for concern? I was wondering if the extra power extractor spring I put in could be causing trouble.

Also, I don't change parts on guns, until I have shot my gun and believe it to be an issue with my specific weapon. You could very well end up causing a problem where there was not one before.

Yep, that makes total sense. In my defense I'll say that I received my rifle without a bcg and so I had to shop for one online, and the one I got said that they did "not support shooting steel cased ammo" and that I'd void the warranty if I did so. Which I don't really care about (the warranty), but I installed the enhanced firing pin and extractor spring thinking it may be needed for reliability.

In hindsight I should have shot it first, if it failed to extract or to ignite the primers then install the "enhancements".

 

[Shadow9mm]

Are you talking about this?

If so, I am going to say no, its not over pressure, and it is an issue with the ejector.

Granted I am used to dealing with brass, but the principal should be the same. When a case is over pressure there are a few signs you can look for

Flowed primers, where the edges are not round anymore, and have flowed to fill the primer pocket

cratered primers, where there is a ring around the firing pin mark where it tried to flow back into the firing pin chanel

ejector marks, where the pressure was too high and it tried to push the casing into the ejector hole.

In the case of ejector marks, that usually means the mark will be protruding from the case head at it tried to fill in where the ejector goes into.

Based on what I am seeing of the case appearing to be dimpled, I would guess the extra power spring is longer or the wire diameter is larger and is not allowing the ejector to sit flush with the bolt face when fired, creating the dimple in the casing.

Also, from what I can see the primers look fine, and in my experience ejector marks come after primer issues, but again, that is just my experience.

For what its worth, I would swap back to the factory ejector spring and see if the issue goes away.

In regards to steel ammo and your bolt. Steel tends to wear things out faster, and can be rough on extractors since they are snapping over the rims regularly. My guess is this is why they wont warranty it. If it were me I would buy an a few spare extractors, extractor springs, and pins as backups just in case as you will most likely need them eventually anyways if you get to shoot regularly. Especially as 7.62x39 bolts are less common than the 5.56 bolt parts.

 

[Pistoler0]

Are you talking about this?

No, I was referring to these:

I think that these are from the extractor's claw grabbing the case, and I was wondering if they indicate a problem or if it is normal for extractors to leave a slight mark on the rim of the casing.

For what its worth, I would swap back to the factory ejector spring and see if the issue goes away.

My bad, it is the tiny little extractor spring that I changed, not the ejector spring. So this is what I put in:
https://www.brownells.com/rifle-parts/bolt-parts/extractor-parts/extractor-springs/ar-15-m16-extra-power-extractor-spring-prod16488.aspx

I didn't change the ejector spring (I don't even know what it is )

 

[Shadow9mm]

The extra power EXTRACTOR spring will make the claw stiffer. it will grab the casings more securely, but as you saw it will make more of a mark on the casing as it rides over the rim to grab on. As long at the gun is reliably pulling the spent casings out of the chamber and kicking then out the side your good to go.

 

[Pistoler0]

The extra power EXTRACTOR spring will make the claw stiffer. it will grab the casings more securely, but as you saw it will make more of a mark on the casing as it rides over the rim to grab on. As long at the gun is reliably pulling the spent casings out of the chamber and kicking then out the side your good to go.

Yay!

Thanks mate, I owe you a beer.
I'll have one on your behalf come to think of it. : )

 

[Shadow9mm]

Glad to help. Sorting out a new type of firearm can be a bit of a learning curve. For me though, understanding exactly how it functions is important, that way I know how to diagnose and fix any problems I might run into.

 

[Sweet Shooter]

Pistoler0, The extra power spring is a good move. Did you include the insert and o-ring (https://bravocompanyusa.com/bcm-extractor-spring-upgrade-kit/). They are a good idea as a matter of course, and will only improve reliability. The marks on your cases are cause during chambering, when the extractor snaps over the case rim. Not caused during extraction.

 

[Pistoler0]

Did you include the insert and o-ring.

I included the insert but not the o-ring, as I read that the extra power spring might be enough. First two mags I shot extracted fine.

 

[HWS]

Your extractor is putting claw marks on a steel case. Congratulations. I would say it is working at 120%.

 

[Sweet Shooter]

Pistoler0 said:

I included the insert but not the o-ring, as I read that the extra power spring might be enough. First two mags I shot extracted fine.

Your first two mags are near irrelevant, confidence boosting—yes, but it's (always) the next one you need to concern yourself with. I use the O-rings too. The extra power spring can (will) fail before an O-ring. You can't go wrong using all the three pieces. Using all three pieces divides the work. It will not hurt your extractor—even with steel cased ammunition (assuming you're using a mil-spec extractor).

It's especially good to run all three pieces if you're shooting steel cased ammunition, as steel is slower to release from the chamber wall than brass.

 

[stagpanther]

Your extractor is putting claw marks on a steel case. Congratulations. I would say it is working at 120%.

+1

There is such a thing as "overpowered" extractor, which is probably why it would have been a good idea to try a bunch of different types of ammo before choosing elective surgery. Sometimes extractor damage to the case can be a barometer for timing issues with your gas system as the bolt tries to extract the case from the chamber before the case has relaxed. An "over-aggressive" extractor can hang onto the rim, flipping it back into the case deflector and causing more damage to the case neck and mouth than you might normally get, though that is more of an issue for folks who like to reload. I wait for obvious signs like failure to extract, double stacking etc before opting to power up the ejector/extractor.