sasquatch981

Failure to Extract after non-fire.

14 posts in this topic

Just follow with me for a second.  I just got my tax stamp, so I can now put the evil upper and lower half together.  Took it out to the range for some testing, and was having issues.  It appears that my rifle does not like my ammo maybe 50% fired.  No problem, the ammo I had on hand had used small rifle primers instead of of small pistol.  I thought this might be an issue so a buddy lent me some of his ammo with pistol primers and the everything went bang.  

 

However when trying to source the solution, I thought it might be the trigger being to light, or possibly the bolt and FP combo being too short etc..  Parts are an Aero Upper, KAW Valley Precision 8.5" Barrel, and a generic 9mm Bolt cut for Glock mags.  Palmetto State Glock Lower, and A Velocity Triggers 3lb flat trigger.  The buddy that lent me his ammo also lent me his JP bolt to see if my bolt was the issue.

 

As stated above once I changed to his ammo everything went bang so no issues with the trigger etc.  However when I went back to my ammo, and switched bolts again, I noted that when all my ammo would not go bang, when I pulled the charging handle back to eject the dud round, it would not extract it.  I thought this might be an issue with the generic bolt, and swapped to the JP.  JP did not fire my ammo, and would also not extract the duds either.  Even had (1) round of my buddies ammo that did not go bang, and when I tried to extract that one, it did not extract.

 

Any ideas?  2 bolts same issue.

 

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The throat (just past the chamber) is too tight. Go back and read the threads about reaming barrel throats in this forum. I had to open the throat in my KVP/Faxon barrel.

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Your hammer spring might be too light to power through the firing pin springs in the bolts. It has happened in my AR9 and .22lr AR's.

 

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Have you tried the "plunk test" with your ammo?

 

What bullet are you loading and what is the OAL?     If its much over 1.100" (shorter still with some bullets) that's your problem.     But then its a simple solution, load shorter.

 

My load is 147 gr X-treme RN bullets loaded to 1.085".

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Hello: The KAW valley barrels are pretty hard and very hard on the reamer. Sounds like either sizing issue or you are loading too long for that chamber. I have had to ream out the KAW valley 16" barrels so I could load to 1.145" OAL and Acme 147 grain bullets. Do the plunk test as advised above and see what you have. Thanks, Eric

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The throat (just past the chamber) is too tight. Go back and read the threads about reaming barrel throats in this forum. I had to open the throat in my KVP/Faxon barrel.

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Yep, I would bet money this is correct.


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Ran the plunk test, and it appears I am too long.  Buddies ammo is 1.125 with 124GR MG's.  Worked fine.  My MG 115's are 1.136, and the 147 plated extremes are 1.150.  I'll crank out some 1.100's with the small pistol primers and see how that works.  Thanks guys.

 

 

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Well, hope you have found your problem?. You might consider using a dummy test round left purposely "long", mark the bullet with a marker or dye  and let the bolt slam the dummy round into the chamber.... After a few trials you will know the correct OAL for your chamber. (leave some free bore, some gunsmiths recommend .005)

 

Edited by mike NM
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A super scientific but not always accurate method to check how long you can load a particular bullet is the dowel test.  (Cleaning rods work too.)

 

Make up a bullet silly long (no powder and no primer).  Place the silly long bullet in the chamber and ease the bolt down on it.  Insert the dowel down the muzzle.  Let it rest on the bullet and mark how far down the barrel the dowel sits with a razor blade.

 

Now remove the bullet and close the bolt.  Repeat the measurement.  The difference between the two marks on the dowel is the length of a bullet that sit in the start of the rifling.

 

I'll repeat this several times each time with a new dummy round to try to be as accurate as possible.

 

Decrease the OAL of the bullet a bit (I'll load .015" to .020" shorter) and give that a try.

 

Bill

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Thanks Bill,  I just went through that process with my PRS rifle to find the max OAL that my rifle likes for load development.  Didn't think of doing that for this problem, but what a great idea!!!

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I had an issue on the first 9mm ar I built with a mix of parts would do the same thing in regards to the FTE's.  The extractor was not hooking on the case until they would fire.  If I had a round left I had to pull it free with my finger nail.  I cut my extractor a little thinner and have had no problems since.

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I had this happen, too. When you say cut the extractor thinner can you show a picture or explain? What BCG? What barrel?

 

gerritm

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I had an issue on the first 9mm ar I built with a mix of parts would do the same thing in regards to the FTE's.  The extractor was not hooking on the case until they would fire.  If I had a round left I had to pull it free with my finger nail.  I cut my extractor a little thinner and have had no problems since.

That's a band-aid fix for the real issue of lack of free bore in your barrel. Loading shorter or reaming your barrel are the long term solutions to stop the problem.


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