AR 15 failure to extract

djt

July 09, 2015 02:22

i built a anderson lower and upper ar15 with good parts, used a stag bcg i had from a stag i have, but changed the bolt in it. test shot the anderson twice with no problem, sold it, he tried to shoot it and is getting a failure to extract,brass pmc ammo, his 2nd shot f.t.e. he cleaned barrel again and tried again, it did it again with no magazine in place. could it be
1. it needs a bigger buffer weight
2. the bcg needs the extractor polished and possible the ejector get a new spring and o ring
3. a gas problem,again i only shot it twice with winchester brass and it did fine with those. any suggestions ?

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  Mobuck

  July 09, 2015 03:56

  Normally, new bolts don't need parts replaced. Some lube on the extractor and ejector might help. It could just be some "new parts break-in" hiccups. Six shots through a brand new rifle is still in the questionable function stage. You used Winchester factory loads for your 2 shot test? I'd like to know what sort of gas and buffer set-up you assembled before adding any more suggestions.
  
  " test shot the anderson twice with no problem,"
  
  My usual start-up takes at least 5(more often 10) shots before I turn a rifle loose to a customer.

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  djt

  July 09, 2015 09:18

  low profile gas block, bolt is a used bolt, maybe 100 rounds shot with it. yes 2 shots, that is all i do when i build them, your right i should go 5 to 10 on shots. never had this problem before, i am leaning towards maybe the the bolt needs took apart and cleaned again.

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  jonk

  July 09, 2015 09:55

  Did the bolt jump the rim and go back, or did the gun not cycle at all?

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  djt

  July 09, 2015 14:16

  it jumped the rim

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  Ray Boone

  July 09, 2015 14:36

  Since the extractor is jumping over the rim, I'd check the rim to see if they are beveled instead of perpendicular to the bore, but most likely, the extractor should be slightly undercut so that the tip contacts the rim first and pressure on it will push it into the rim rather than sliding away and over the rim.

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  USN_Airdale

  July 10, 2015 05:08

  PMC ammo is Korean made, not high quality, try American made ammo and come back with results.., OK ?

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  burpfire

  July 10, 2015 05:36

  First try a new buffer. This is one of the most common problems I find. If it is overgassing you need to slow it down with a heavier buffer.

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  djt

  July 10, 2015 14:53

  thanks for ever ones help, i do appreciate it.

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