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My grendel build with a AR Stoner barrel has started having issues with spent case extraction. I seem to remember some chamber issues with early barrels. Anyone else had any experience with this?
Thanks
Check your extractor if you have been firing steel cased ammo it may be damaged. If it good it could be a under gassed problem. Fires the round and doesn’t cycle back far enough to eject the casing.
Is the spent case left in the chamber, or does it get left in the action on top of the magazine?
I'm either sharing this thread, or hijacking it. Hope it's the former.
Recently ran some function testing on a new build. Fired 3 rounds of factory Black. Two ejected to about 5:00 and one just dribbled out of the action and fell next to the rifle. Fired a ladder of 123 gr SST's over CFE from 29.4 to 31.5 gr, with 0.3 gr increments. First case dribbled out, second case was laying on the mag follower, third ejected to about 3:30. The rest of the reloads either stayed on the follower or dribbled out. All of the rounds were singled loaded into the mag, and the bolt locked back properly each time.
I then swapped out bolts and repeated the test above. All of the factory rounds ejected to about 5:00 and all of the CFE reloads ejected to about 4:00. The replacement bolt has an insert under the extractor spring and the faulty one did not.
Before I even allow a barrel to go near an upper receiver, I make sure the chamber and bore are clean and clear.
I then take several factory loads and dummy cartridges that I have to see that they will fully chamber and fall free from the chamber.
I use a stripped bolt to test that they fully chamber and that the bolt will rotate.
I remove the bolt, then see if the cartridge will fall free.
If the cartridges get stuck, I take one of the dummies with a black-colored ogive, and see if the lands are being jammed.
For the few barrels I've had come through that were like that, I have always been able to see the rifling marks on the ogive, indicating a short throat. I can think of 3 barrels off the top of my head that were like that. The rest have been fine.
Some chambers on economy-grade barrels have tooling marks and imperfections all inside the chamber, so when the case obturates to the chamber wall, it has more purchase strength to the wall than the BCG and extractor can overcome, so the extractor slips off the rim and you get a FTExtract stuck case malfunction.
These chambers either need to be finish-reamed and polished or just polished, depending on how they do with the chamber check with cartridges.
Was this happening with factory ammo or hand loads, and what type of ammo?
NRA Basic, Pistol, Rifle, Shotgun, RSO
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
I hate it when people start a thread asking for help, and never reporting the outcome! I've been reading about the "cycling" problems of many folks. I try to do as much research as I can so as not to clutter the site with "dead horses". I am very grateful for the sharing of time, experience, and troubleshooting on this site, and I wish everyone had a little more consideration to report their results to help others with a similar problem. Thanks to all who make this site a blessing for so many.
When a man's ways please the Lord, He makes even his enemies to be at peace with him.
Well,
Sorry it has taken a few years for me to get some time to put back into this. I have yet to resolve my issue. At the time of my previous post, I tried many levels of cleaning, but the issue would not go away. I recently contacted Satern Barrels (who owns Liberty Barrels), and sent the barrel to them for inspection. I just got the barrel back and will put the gun back together soon. I'll let you know what happens as soon as I can get a little time on the trigger.
I haven't re-installed the barrel yet, but did get clarification on the work that was done at Satern, which was removal of the compound throat of the original Grendel chambering. So I guess now, as far as I understand it, I basically have a Grendel II chamber? As soon as I sling some lead, I'll update this thread.
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