6.5 Grendel Failure to Eject

Stirling XD

Stirling XD

New member
I had a spare Rock River upper that I decided to convert to a 6.5 Grendel. I bought an 18” AR Stoner a barrel (Grendel II) and bolt from Midway. The first 12 shots worked well. Then I started having failures to eject that progressed into failures to extract. The bolt would also try to load a fresh shell. I cleaned everything thoroughly and continued having the same problem. The bolt just would not pull the spent shell out of the chamber.

I removed the gas block and tube and can't find any problems. And since the bolt locks on an empty mag, I think my problem is elsewhere.
I decided the replace the extractor spring with a heavier one and added an O-ring. The next trip to the range went much like the first. The first 10 rounds fired fine, but by the time I got to round 25, the only way to remove the spent shell was with a cleaning rod. It was still trying load a fresh round. The bolt always locked open on an empty mag. I am shooting Hornady Amax 123 grain ammo.

Based on some of the other posts I’ve read, I may need an adjustable gas block. But I’d like to get some other opinions. I’m also wondering if I may have a defective bolt or barrel.
 
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When it fails to extract, is the extractor slipping off the rim of the case, or is it still attached but won't pull it out of the chamber? If it's slipping off sounds like an extractor issue. If not maybe gas issue. Either way it could also be a chamber that's a little rough. How does the brass look coming out? All scratched up or not? Just some stuff to look for.
 
Originally Posted By: 204 ARWhen it fails to extract, is the extractor slipping off the rim of the case, or is it still attached but won't pull it out of the chamber? If it's slipping off sounds like an extractor issue. If not maybe gas issue. Either way it could also be a chamber that's a little rough. How does the brass look coming out? All scratched up or not? Just some stuff to look for.

The extractor slips off the case and leaves it in the chamber. If I pull the bolt back and let go, it re-seats on the empty shell and then slips off when I pull the bolt back again. There is a longitudinal scratch on most of the shells from just above the rim to the shoulder, but it looks like it's more from feeding or ejection. I didn't examine each shell after each shot. I will do that in the future. I can also see where the extractor slips off of the shell.

I already swapped out the extractor spring for a heavier spring with an o-ring. (RSM USA 2 Extractor Upgrade Kit - Amazon). Do I need an even heavier spring? Would adding a second o-ring help? Or should I send the bolt and barrel back to Midway?
 
Try cleaning the chamber really, really well. We have found that some of the chambers can be a bit rough, and the 6.5's can be a dirty burner and builds up a lot of carbon very quickly. You might need to clean it and polish the chamber up a bit.

If you have already changed out springs I would check out the spring that you removed and see if it is different than the one that you put back in.

Recently we have found that some companies are using springs as small as .021 in diameter that will have issues like these. Usually thicker springs are better. If your spring is not thick enough then it cannot fight the tension of the ejector spring. If you have a lot of longitudinal scratches on your cases then this might be happening.

You can also have an issue with the gas port. Dwell timing is the big issue with gas port diameter. If the port is too small then the bolt is not unlocked soon enough and you lose the energy necessary to adequately eject the casing. Essentially the BCG is just taking the empty case back with it and trying to run another shell in without having ejected the empty.

I hope this helps.
 
If you're getting reliable lock back on the bolt carrier, I wouldn't think it's under-gassed. Mo made good suggestions about the gas port diameter/dwell issue and the rough chamber possibility. Before I started down either of those roads, though, I'd take another look at the spring.

I have no idea what extractor spring RSM uses in their kits. Some years ago I had the same problem. I bought several Wolff extra-power springs and black inserts. Installed one and the rifle has been dead nuts reliable ever since. You might also take a look at the extractor. If the inside face of it is rounded or otherwise not parallel to the bolt face the extractor might be levering itself off the case on extraction.

Good luck.
 
Originally Posted By: rg Another very important modification is polishing the extractor. Along with rounding the tip of the ejector pin and polishing my extractor in my 6.5 Grendel it has made it reliable. I was having the same issues as you before. Here's a link to polishing the extractor. Scroll down in the post for pictures:
http://blackholeweaponry.proboards.com/thread/1538/say-goodbye-extractor-separation-issues

Thanks for both of the suggestions and the links. I will give them a try and let you know how they work.
 
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