Help...failure to extract a spent round

[Sojorboy]

Good evening everyone I need your help. My friend and I recently purchased 2 6.5 grendel uppers, his new, mine slightly used. Today he carried both rifles to the range to sight in the optics for us. Both rifles fail to remove the fired round. The BCG is leaving the fired round in the chamber, travelling reward, picking up another round from the magazine and jamming it into the rear of the fired round still in the chamber. A total of 5 different ammo were tried, 2 different rounds of AA, Blackhills, Hornady and Wolf Gold. The same results were repeated from both rifles with all the ammo mentioned. But, when the mags were loaded and the bolt worked manually, everything functioned correctly. Only when the rifles were fired did the empty case stay in the chamber. I'm new to the AR platform and would apprecite any help you guys can give.

Thanks Guys S.Boy

[Drifter]

My guess is that the hook on the extractor isn't sufficient to hold on to the case rim. It's a relatively easy fix (if you have a spare).

How difficult is it to remove a spent case from the chamber when this happens? Is it lodged in tightly, or does it come out with relative ease?

Do you (or a friend) have another working Grendel that you could borrow a bolt from (or just the extractor if there's a headspace issue with an alternate bolt) to test in the new uppers?

[Sojorboy]

The spent cases lodged in the chamber have to be removed with a pry bar/screw driver.
1 round in particular required a plunger from the front end of the barrel.
The bolt is jamming them in there pretty tight when it tries to feed the second round.

No I don't have another Grendel or know anyone close to me who does.

[LRRPF52]

If the rounds are seizing in the chamber from all those manufacturers, it sounds like excessively tight chambers. Who made the barrels? Where were the uppers purchased from?

[Sojorboy]

The used upper is a 16" GDMR from AA and the new upper is a 24" Bull from J&T Dist. I plan on calling both parties on Monday if I can't resolve this problem before then. I did contact the previous owner of the used AA. It has minimal use as he only shot it a few times (12) to sight in the scope he had planned to use on it.

[bwaites]

But if the chambers were so tight as to inhibit extraction, wouldn't they be too tight to allow the round to even feed?

I'm wondering if these might be 7.62x39 bolts, which don't allow the rim to drop deep enough that the extractor has good purchase on the rim. They will often hand cycle until fired, but that little extra case adhesion after firing will keep the extractor from having enough grip to yank it free.

So, it comes down to LRRPF52's question: Who built them, and where did they come from? Are they actually Grendel chambers or someone else's?

[bwaites]

The used upper is a 16" GDMR from AA and the new upper is from J&T Dist. I plan on calling both parties on Monday if I can't resolve the problems before then.

Ok, well, assuming no one swapped stuff, those should be proper bolts.

Something ain't right, because chances that 2 rifles from different manufacturers would have the same issue are astronomically low. The GDMR probably has a cut rifled Satern barrel, the J&T probably a button rifled Shaw.

Chamber a single round, drop the mag, fire, and see if it will eject. If it does, then load a single round in the mag, chamber the round, leave the mag in place, fire, and see if the round ejects. If it does, load two rounds in the mag, chamber one, and fire, see if the round ejects. If it does, repeat, adding a round each time. If the round does not eject at any point, return here and report.

[Sojorboy]

Bwaites, I have to agree this is astronomical ! Unfortunately neither one of us are going to be able to shoot the rifles this weekend. As soon as we can I'll follow your instructions and report back here. Thanks

Side note..3 different mags were used during the outing. A used 10 round and two new mags from Midway USA (10 and 20 round mags)

[bwaites]

I'm not convinced or even suggesting it is the mags, but it may be something to do with how the mag, bolt carrier, and catch are interacting.

It's too bizarre to believe that two rifles are having the same exact issue, when built by two different manufacturers. Compound that with the two of you getting the rifles, and knowing each other, and taking them to the range the same day......Wild!

[Sojorboy]

Yes it's pretty wild and a little frustrating getting your first AR and it's no better right now than a single shot Daisy !
Here's a little more info on rifles. The AA GDMR is actually 1 of the older model AAs with the LW barrel. I do believe the J&T has the Shaw. The AA is on a RRA lower and the J&T is on a DPMS. Both lowers function flawlessly with the 556/223 uppers. Triggers have been change to RRA national match 2 stage triggers. The AA sports a Magpul PRS stock and the J&T a 6 position colapseable. No changes have been made to the uppers to my knowledge.

[leopard6.5]

Bill: The used upper Sojorboy has is the older GDMR from AA back when they used the L/W barrels. Guess how I know?

Was L/W using the .295 neck back then? I thought they always used the .300 neck until the split-up.

This upper was sent back to Bill A. when new because the shells were hanging up when I was hand cycling it to make sure everything worked okay before I fired it.
If I remember right( this was 3-4 years ago at least), Bill said he filed off some sharp edges, I think on either the extractor or the bolt, I don't remember which.

Bill said he then fired it and everything worked okay. When I got it back, I fired 12 rounds of Black Hills ammo to sight in a scope on the upper and it's been in the safe since.
It fired perfectly for those 12 rounds.
I was also struck by the fact that both uppers were doing the same thing.
I hadn't thought about the magazine issue. Good idea to at least check.

I just thought I should jump in here to give further info so it may give you guys a better idea what the upper is and has been through. Hopefully it helps.

Lee

[bwaites]

Thanks Lee!

CSS sold some rifles/uppers with .295 necks as "Grendel Match" chambered rifles, but if it was a GDMR, then it was an AA rifle, and should have a .300 neck. AA never sold the .295 neck, as they were a special order CSS only option.

What you described is a typical issue with new extractors. Some of the edges are so sharp they will "Bite" the brass. Now I'm wondering if the extractors somehow got damaged.

[Sojorboy]

Thanks for the info Lee. Bill, I honestly don't know of anything we could have done to damage the bolt. I was not present for the shoot yesterday but prior to, all I know of that was done to the uppers are as follows. They were unpacked, assembled onto the lowers, scopes were mounted and a magazine was loaded with ammo. It was then hand cycled throught the rifles to make sure things were "safe to fire" before going to the range and pulling the trigger on a live round. The rifles were then cleaned with Rem oil and put back in the safe until yesterday. How hard/easy is it do damage a bolt ? What are some of the common causes of bolt damage ?

[bwaites]

Bolts require a lot to damage them, extractors, though part of the bolt, are essentially thin pieces of spring steel, and much easier.

Can you get close ups of the bolt especially the extractor area?

[Drifter]

The rifles were then cleaned with Rem oil and put back in the safe until yesterday.

Check to make sure that the extractor isn't coated in oil, as it might make the cartridge rim more likely to slip from the extractor's grasp.