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slimjim Super Member


Joined: May 16, 2009 Posts: 8317 Location: Fort Worth TX
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Posted: Sat Sep 15, 2012 8:15 pm Post subject: Troubleshooting |
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I'm making some progress on my new AR build in 6.8. Accuracy hasn't been the best so far. Got some groups under 2 MOA this third time out. A concern is the brass is forming with an indentation. Do you think this is an irregularity in the chamber wall? Should I be concerned? This is factory Hornady brass, once fired with 110 HPBT.
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_________________ "To anger a conservative, lie to him. To anger a liberal, tell him the truth." - Theodore Roosevelt
"The world is a dangerous place to live; not because of the people who are evil, but because of the people who don't do anything about it." - Albert Einstein |
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Elvis Super Member


Joined: Jul 27, 2008 Posts: 9359 Location: south island New Zealand
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Posted: Sat Sep 15, 2012 9:13 pm Post subject: Re: Troubleshooting |
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the dents are 45 degrees across case??see if you can bore scope the chamber to find the cause. it could be my eyes or the photo but those cases the top one and one 4th from left look as crooked as all heck eg not at right angles to the base??
_________________ You shot it You pluck it !
Them who eats the most duck eats the most feathers! |
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DallanC Site Admin


Joined: Jan 18, 2005 Posts: 3600 Location: Utah
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Posted: Sat Sep 15, 2012 9:51 pm Post subject: Re: Troubleshooting |
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Its either a malformed chamber or a very dirty one. Try cleaning it first... with some *MILD* abrasive. If it still persists you might want to consider a chamber casting.
-DallanC
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Elvis Super Member


Joined: Jul 27, 2008 Posts: 9359 Location: south island New Zealand
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Posted: Sun Sep 16, 2012 12:07 am Post subject: Re: Troubleshooting |
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looked again and got another set of eyes to look aswell. that 1st case looks like case mouth is not at right angles either. whats the story morning glory???
_________________ You shot it You pluck it !
Them who eats the most duck eats the most feathers! |
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Ominivision1 Super Member


Joined: Sep 20, 2010 Posts: 2984 Location: Iowa
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Posted: Sun Sep 16, 2012 1:32 am Post subject: Re: Troubleshooting |
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Those shells look exactly like the ones a shooting buddy bought over for me to look at. He was firing wolf steel cased ammo which has some kind of coating on them and he then fired some of his handloads which looked like yours.
Clean the chamber and barrel first.
_________________ Regards
Limitations are but boundaries created inside our minds. |
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slimjim Super Member


Joined: May 16, 2009 Posts: 8317 Location: Fort Worth TX
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Posted: Sun Sep 16, 2012 3:51 am Post subject: Re: Troubleshooting |
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Elvis wrote: |
it could be my eyes or the photo but those cases the top one and one 4th from left look as crooked as all heck eg not at right angles to the base?? |
Its the camera lens, Elvis. Your eyes are fine. Its an inexpensive digital camera I picked up on vacation. Get much off the center of the image and there is noticeable distortion. I had to adjust the angle of camera to get the light right and the cases ended up off center in the image.
_________________ "To anger a conservative, lie to him. To anger a liberal, tell him the truth." - Theodore Roosevelt
"The world is a dangerous place to live; not because of the people who are evil, but because of the people who don't do anything about it." - Albert Einstein |
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slimjim Super Member


Joined: May 16, 2009 Posts: 8317 Location: Fort Worth TX
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Posted: Sun Sep 16, 2012 3:52 am Post subject: Re: Troubleshooting |
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Ominivision1 wrote: |
Clean the chamber and barrel first. |
Ok, clean the chamber first. Maybe use some mild abrasive.
But for the sake of discussion, so what if it remains? Is it an issue? I had an M1 with a tooling mark in the chamber and it was affecting extraction. Extraction on this one is the best of any of my ARs. Its the accuracy that is concerning me. It started out at 3 MOA the first two times out. I've been measuring and inspecting every little thing I can find. This third time out (with about 60 rounds already through it) it seem to settle down and was shooting 1 1/2 to 2 MOA. With some more adjustments, there might be some light at the end of the tunnel.
_________________ "To anger a conservative, lie to him. To anger a liberal, tell him the truth." - Theodore Roosevelt
"The world is a dangerous place to live; not because of the people who are evil, but because of the people who don't do anything about it." - Albert Einstein |
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Vince Site Admin


Joined: May 25, 2005 Posts: 15935 Location: Brisbane AUSTRALIA
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MacD Super Member


Joined: Apr 08, 2011 Posts: 1052 Location: Canada
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Posted: Sun Sep 16, 2012 5:37 am Post subject: Re: Troubleshooting |
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My only suggestion is to mark a casing before firing with felt marker. Load the round with the mark at 12 oclock and then inspect the fired case to locate the deformation relative to the mark. This will identify the suspect surface area in the chamber. The chamber cast is the best tool. This will allow measurement of roundness, taper and that the axis is true. If it isn't dirt I suspect the boring or reaming was botched. The deformation looks like a twist.
_________________ La a'Blair s'math n Cairdean
(Friends are good on the day of battle)
Last edited by MacD on Sun Sep 16, 2012 4:15 pm; edited 1 time in total |
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TRBLSHTR Super Member


Joined: Mar 23, 2007 Posts: 1071 Location: Lower 48's-left coast(near portlandia)
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Suzanne Super Member


Joined: Jun 27, 2009 Posts: 3323 Location: Eugene, Oregon
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Posted: Sun Sep 16, 2012 10:20 am Post subject: Re: Troubleshooting |
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Just what I was gonna say.....(no really) remove the gas so you can chamber one round and eliminate the ejection question. I don't actually see how it could hit at such an angle, but I wonder if you added anything to the original extractor (like stronger spring, or D-ring, O-ring or spring buffer) if so, you might have too much extraction? I dunno, just a guess. Personally I'd check the extraction issue first because I'd think you would be able to see a chamber deformity making a dent that obvious.
Suz
_________________ May the moon keep you centered,
May the sun keep you dancing,
And the stars shed light on your dreams. |
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Ominivision1 Super Member


Joined: Sep 20, 2010 Posts: 2984 Location: Iowa
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Posted: Sun Sep 16, 2012 11:52 am Post subject: Re: Troubleshooting |
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Boy my eyes must be getting bad because I took Slim's pic and enlarged it 500% and cannot see any indentation. If there is, definitely check your chamber and take pics using the macro mode and also be aware like Troubleshooter and Suz said that the brass might be hitting the deflector.
Here is an example of bad chambers on ar15's
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_________________ Regards
Limitations are but boundaries created inside our minds. |
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slimjim Super Member


Joined: May 16, 2009 Posts: 8317 Location: Fort Worth TX
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Posted: Sun Sep 16, 2012 12:11 pm Post subject: Re: Troubleshooting |
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I have a DPMS upper without a deflector. I should be able to mark the case as MacD suggested and not have to fool with the gas tube. I definitely will give a good cleaning and inspection before I go out again.
_________________ "To anger a conservative, lie to him. To anger a liberal, tell him the truth." - Theodore Roosevelt
"The world is a dangerous place to live; not because of the people who are evil, but because of the people who don't do anything about it." - Albert Einstein |
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slimjim Super Member


Joined: May 16, 2009 Posts: 8317 Location: Fort Worth TX
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Posted: Sun Sep 16, 2012 12:14 pm Post subject: Re: Troubleshooting |
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Ominivision1 wrote: |
Boy my eyes must be getting bad because I took Slim's pic and enlarged it 500% and cannot see any indentation. |
OV1, its there. I resized them and the indentation remained like a hook up near the shoulder. I should be able to take picture of my chamber like you suggested with my digital camera. I'll wait to see if it returns after a good cleaning.
_________________ "To anger a conservative, lie to him. To anger a liberal, tell him the truth." - Theodore Roosevelt
"The world is a dangerous place to live; not because of the people who are evil, but because of the people who don't do anything about it." - Albert Einstein |
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Elvis Super Member


Joined: Jul 27, 2008 Posts: 9359 Location: south island New Zealand
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