Extractor problem with new Brownells bolt

[random157294683]

Hi, everyone! Nice little forum you've got here. It's helped a lot with my research. I fixed an issue with my newly built Grendel and thought I'd try to document my issue here in case someone else encounters the same.

The important parts of my gun:
Brownells 24" barrel and bolt
AIM BCG-X bolt carrier
Gibbz G4 Side-Charging Upper

From the very first shot with my 6.5 Grendel I had ejection issues. The cases that did manage to eject were barely dribbling out. I had the same issues when cycling the rounds through by hand, so I knew it wasn't gas related.

I tore apart every AR bolt I had on hand and inspected the extractors. The corners of the Grendel bolt extractor were significantly less rounded than the 5.56 ejectors. Here's a picture of what I'm talking about. I thought this might simply be because of the larger circumference of the round, but as I played around a bit I found that these sharp edges were digging into the rim of the brass and not allowing it to free itself from the extractor when tilted. Here's another picture.

I decided to use a dremel and round them off a bit. I ended up taking off a bit more material than I had planned, but not too bad. Here is a picture of the modified extractor.

The gun is running great so far. I've manually cycled 20 rounds and fired 20 more. I'm getting a nice strong consistent ejection to about 4 o'clock.

For anyone who wants a closer look, I've got YouTube videos up documenting all of this.
Here's my initial range trip where I had all of the problems.
Here's the video comparing the extractors and modifying the one for my Grendel.
Here's the follow-up range trip where the gun runs great with the modified extractor.

[devildogandboy]

welcome to the forum! really nice vids, well detailed in showing how to remove the spur on the extractor.

Bruce

[BluntForceTrauma]

Great info and thanks for taking the time to document it!

[montana]

Great video's and information on extractor fix for the Grendel. Much appreciated, thank's for sharing.

[LRRPF52]

This is one of the first things I do as part of a 6.5 Grendel build.

I also take the sharp edge off the bolt face/extractor pocket ledge, and the rear face of the extractor, as those parts will shear brass during primary extraction.

I also chamfer the ejector. There are a bunch of little tweaks you can do to improve performance and eliminate possibilities of things hanging up, shaving brass, etc.

Do you have the reloading handbooks by the way?

[random157294683]

Thanks for the kind comments.

I also take the sharp edge off the bolt face/extractor pocket ledge, and the rear face of the extractor, as those parts will shear brass during primary extraction.

I also chamfer the ejector. There are a bunch of little tweaks you can do to improve performance and eliminate possibilities of things hanging up, shaving brass, etc.

I was thinking about doing the ejector chamfer while I was at it but decided to make sure the extractor was operating okay first. One variable at a time and all that. I might go back in and clean things up a bit more.

I need to do some work on the feed ramps and lugs, too. I noticed most of the brass ended up with racing stripes down the side. :/ It's not too bad, but a little polishing should go a long way.

I don't have your handbooks. I might look into those.

[Drillboss]

I agree completely on the quality and content of the videos. While looking at the mechanics of how the brass locked up on the extractor in your video, I wonder if very light smoothing of the extractor teeth along with removing some material from the front, outer edge of the extractor would allow the brass to release without concern about how the extractor pulls the brass out of the chamber. Would there be any downside to grinding off that outer edge?

Just a thought, kudos on identifying and correcting the problem.

[VASCAR2]

New mag feed lips will leave longitudinal scratches on brass as well as the barrel extension/feed ramp.

[tommag]

Thanks for the excellent videos. My extractor was hanging on to the empties and trying to feed some of them back in with the loaded round. I just spent a few minutes with the edge of a whet stone and some fine sandpaper, it seems to let go easier now.

[random157294683]

I agree completely on the quality and content of the videos. While looking at the mechanics of how the brass locked up on the extractor in your video, I wonder if very light smoothing of the extractor teeth along with removing some material from the front, outer edge of the extractor would allow the brass to release without concern about how the extractor pulls the brass out of the chamber. Would there be any downside to grinding off that outer edge?

Just a thought, kudos on identifying and correcting the problem.

I get what you're saying, but I think that might make matters worse. I assume that top pivot point helps start the "kick out" to help the rim clear the extractor. I don't know for certain...I'm definitely no expert on the mechanics of how all this operates.

[random157294683]

New mag feed lips will leave longitudinal scratches on brass as well as the barrel extension/feed ramp.

Yup, that was my first hope. I'd much rather modify a magazine than a barrel extension! But, looking closely at the marks and the spacing between them, it is definitely the barrel extension.
I'll probably make another video about it.

[LRRPF52]

The neck hits the barrel extension teeth during extraction, because of ejector tension, as soon as it clears the chamber.

Be careful with modifying the lead edges of the extension teeth, because they are surfaces under extreme load during combustion.

[random157294683]

The neck hits the barrel extension teeth during extraction, because of ejector tension, as soon as it clears the chamber.

Be careful with modifying the lead edges of the extension teeth, because they are surfaces under extreme load during combustion.

Yeah, I noticed that on closer inspection today. The neck scratches are not flattened or covered with carbon fouling, so I figured it must be happening during extraction. They are not deep scratches, so I don't think I'm going to mess with the chamber-side edge of the teeth. I would need to remove the barrel to get at it as well as I'd like, and it's not bad enough to warrant that much effort.

I'm also getting gouges in the case rims that are closely aligned with the neck scratches, so I think that must be from my extractor. I'll have to polish it up a bit more.

Here's a crappy picture.

[am4966]

This is one of the first things I do as part of a 6.5 Grendel build.

I also take the sharp edge off the bolt face/extractor pocket ledge, and the rear face of the extractor, as those parts will shear brass during primary extraction.

I also chamfer the ejector. There are a bunch of little tweaks you can do to improve performance and eliminate possibilities of things hanging up, shaving brass, etc.

Do you have the reloading handbooks by the way?

LRR what do you use on the extractor to remove the tits/points on them? What do you use to chamfer the ejector? Since this seems to be a common problem. Maybe we could get a post locked at top. Of page FAQ of trouble shooting or things you should check.

Thx