Gunsmithing LR-308 extraction issue

[junglejim23]

I am stumped here

I have a POF lower and DPMS upper
it is brand new I have maybe 100 rnds threw it my first range sesion went flawless but today I was having all kinds of falure to extract upon checking the cases the case head has been torn by the extractor. looking at the extractor there is some ware and it seems to be rather soft steel

the ammunition i was using was LC 90 on both trips

could the brass have differed some how same year manufactor.
is there any reason my extractor could have failed with this few rnds ?

help this is supposed to be my SHTF rifle

 

[oneshot onekill]

Re: LR-308 extraction issue

I would check the condition of the chamber and then the length of the chamber compared to the cases. The chamber may have been poorly finished and is grabbing your brass too much. I've also had Lake City ammo that didn't fit my precision rifle. Not that your issue is the same, but it's worth investigating. FWIW

 

[jn123]

Re: LR-308 extraction issue

I would make sure the chamber is clean and that there are no brass or metal chips left in there. The LR-308 chambers are known to be a little on the tight side. Did you have the rifle apart after the first trip to the range?

 

[Brain]

Re: LR-308 extraction issue

If the extractor tore the rim of the case off, it didn't fail. Working just like it should.


Chamber, ammo, or gas system are the three things that might cause extraction problems as you described. As mentioned before, dirty, rough, or tight chamber could cause it. Oversized brass will cause it. Gas system delivering too much, too soon to the bolt will cause it as well.

If factory ammo, I'd start with the chamber.

 

[junglejim23]

Re: LR-308 extraction issue

ok so I tore it down last night after my post and this is what I found

1, extractor tore of a good portion of the rim
2, case shows signs of chamber tight at the base of case


I examined all of my brass from the first range trip all of it showed heavy extractor marks some showed minor amount of material removed from the rim but they all had extracted just fine.

I have read that most LR-308's are chambered for .308 win only but mine is marked DPMS 7.62X51 1-10

so the chamber should be set up for MIL ammunition