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Possible .308 extractor issue?


DocMedic

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But does it extract ok?

 

I had a 308 that gave me Hell for too long. my re loads would fall in and out of the Gage. but would stick in the gun.

 

Long story, short,, I ground down, the shell holder,, I just held it on a grinder wheel,   just a lil bit,, I didn't go nuts on it,, , now when I """""Small Base size"""" it also bumps the shoulder back a lil bit..

 

308 ammo works better in all my guns now,,

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Funny thing but I was also shooting my JP 308 a couple days ago and noticed the same mark. I believe the extractor has a slight undercut that should help with extraction by preventing the extractor from slipping off the rim. 

I do the same thing with my 1911 extractors. 

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i was running 168 grain custom comps with varget at 2600 fps out of an 18" barrel. No flattened primers but it was def hot and had some pretty good swipes on the case head until I snapped off my extractor. Little too much gas as it was trying to extract too soon. I replaced the extractor with a Jp and the gas block with an adjustable and turned down the gas a bit. Runs great.

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2 hours ago, Don_B said:

Funny thing but I was also shooting my JP 308 a couple days ago and noticed the same mark. I believe the extractor has a slight undercut that should help with extraction by preventing the extractor from slipping off the rim. 

I do the same thing with my 1911 extractors. 

 

You know what, I just replaced the bolt with a JP308 bolt just before RM3G Last year. I wonder if it's the extractor the comes with the jp

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The brass from my 20" AR10 looks the same. It does not have adjustable gas, and I run factory 147 grain ball for the most part (Privi Partizan lately). I use Freedom Munitions 155 Amax for targets past 100 yards.  My rifle has a stock, full weight carrier and buffer with a JP spring (rifle length buffer system). It is over gassed, but other than breaking an ejector last year, it has been really reliable.

Hurley

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I wouldn't worry about those marks honestly. Perhaps a slighter faster powder would be a bit easier on the brass but otherwise it looks fine. The velocity is in line with reasonable load data as well for that barrel length.

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Most .308s are severely over gassed. Is the spent brass case mouth or shoulder dented?  If not, adjust the gas down till it doesn't cycle and then open it up just a little past where it starts running again and it should be fine. 

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So far, I've only shot SA FMJ through my GII.  Originally it had the factory gas block on it.  Then I installed an adjustable gas block on it.  I've not seen marks like that on my brass with either set up.    I also changed buffers around, early on.  No differences seen.

 

Does it leave a mark just from chambering the rounds and then ejecting them by hand?

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