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270AR Extractor Lip Sheared Off

2K views 9 replies 3 participants last post by  Ed308 
#1 · (Edited)
I've had some teething problems with my 270AR. The first 100 rounds I used to break-in the rife were fired with few issues except for a couple of FTE around the 50 round mark. A little lube fixed that problem. The problem started on my second batch with several ladder test of Leverevolution and CTE. Which one I'm not sure since I had problems over several range sessions, I drop the ammo box at one point mixing the ammo up and due to the passage of time before I sat down today and pulled the bolt to inspect. I do know my COL was 2.65.

When I pulled the bolt, I was surprised to see lip of the extractor missing. Not sure if it is due to hot rounds or a defective extractor. Easy problem to fix but curious about what caused the failure. I was also surprised to see a build of carbon on the boat tail which I thought was odd since I've only fires slightly more that 100 round fired with the bolt and barrel.

Thoughts? Hot ammo or defective extractor? Here's some photos. The photo with the cases, the case on the upper row is the last round fired and that was stuck in chamber. The extractor was already sheared off or had broken by that point since the case wouldn't extract and need a rod to remove. The lower row is for the fired cases. The brass looks really beat up on some of those case. Primers are starting to flatten.

Ammunition Coin Metal


Here's a photo of the bolt and bad extractor (top) plus the one I used to replace it with. Carbon already scraped off the bolt tail in this photo:

Tool


Here's a photo of the top of the bolt:

Lock Finger Hand Button Auto part
 
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#2 ·
i have seen some broken extractors not normal in 100 rounds but it does happen.

one thing to note after firing you need to bump the shoulders .004-.005 for reliable running is what i have found with all the 308 based cats.

you may want to post the loads you were running to get an idea if you are hot or not, i can say lever is very dirty especially if not pushing it hard.
 
#3 ·
7.62x39 extractors are weaker than all the others due to the larger rim diameter. Combine weaker extractors with a large cartridge and that will cause more problems. If the loads are hot and the extractor is trying to jerk them out of the chamber while the brass is stuck to the chamber walls and you have more problems. I only used machined 7.62x39 extractors...only one company in the country makes them. The MIM 7.62x39 extractors used on most 7.62x39 bolts will not last long.
 
#4 ·
It was probably just a bad ejector. And I was starting low on the powder so I thinking I was the Lever loads.

But now another problem. I thought it would be just a simple exchange of extractors. The first time I put it together it work but I was getting two slices in the Lapua brass. So I switch it for another ejector to see if less brass damage. Now the case doesn't eject from the bolt and is mangling the brass. I tried it with several ejectors and spring and won't eject. I've confirm the spring is in with fat side in the ejector plus the small metal insert in the spring. I really hard to get the AR in battery. And when I pull the bolt back the round stays in the bolt and doesn't eject. Can't figure out what I'm doing wrong since the spring only works one way plus a pin to hold the extractor in the bolt. Any suggestions?
 
#9 · (Edited)
Pulled the bullets for the loads I was having problems with last night. The loads were with CFE 38.5 grs and 115 gr Nosler CC bullets. Mild loads. I also checked the shoulder on the brass and found where I had bumped the brass back .005. So, thinking (hoping) my problem was due to a defective extractor. Installed a new extractor in the bolt today. Also switched out the extractor spring for stronger spring and changed the buffer to a Spikes H2 buffer. Scrubbed and polished the chamber. Hopefully these changes will get my 270AR back into service.
 
#10 ·
Finally..., back in business. The new extractor worked. AND NO STUCK CASES with 40 rounds fired! It is slinging the brass to 1-2 clock. I may have switched the buffer from a regular to a Spikes H2. But maybe it's time install an adjustable gas block like most have.

Thanks to Constructor, BigDawg and Texas Hog Man for your suggestions.
 
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