Gunsmithing Polishing up an AR-15 Chamber

danr

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Gent's, I have an AR that will sometimes fail to extract. The case will remain stuck in the chamber. The extractor is good as I replaced the original one but still does the same thing. The stuck case shows where the extractor claw had a good hold so I'm thinking I may have rough chamber. The stuck case will dislodge easily when I push it out with a cleaning rod. It is a factory rifle and it will fail to extract after cleaning with a chamber brush/solvent. My question is, Is there a tool readilly available where I can polish up the chamber myself to see if that takes care of it?
 

Greg Langelius *

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Re: Polishing up an AR-15 Chamber

Hold off just yet. Polishing a chamber will <span style="font-style: italic">increase</span> contact surface area, and may have opposite the desired effect. All things being equal, a properly spec'd AR and ammo should do fine with periodic chamber cleaning.

Questions:

Is this a basic AR-15/M-16 barrel and port configuration?

Is the ammo Mil-Spec 55/62gr, or is it handloads with maybe heavier bullet weights and maybe slower propellent burn rates?

I'm thinking maybe something has altered the timing outside the design specs, allowing a late pressure curve to cause the case to stick.

Greg

 

tiNdvenTFHwMdqKW

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Re: Polishing up an AR-15 Chamber

I had the same thing recently. I was tearing the rim off the cases during extraction. I took a cleaning brush and mounted it in my drill and spun it inside the chamber with a little bit of polishing compound. Then I buffed it with the Dremel. That worked for me.

BUT - my AR is just a "toy" it's not a serious target gun or go to gun. I would have been a little more careful with a gun that I had spent serious money on.

After the polishing the gun shot great and accuracy seemed pretty good for a M4gery. Again, I just use this gun for "fun" so I'm not too worried about it being perfect.
 

border_reiver

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Re: Polishing up an AR-15 Chamber

brush research makes a dingleberry hone that fits the .223 chamber nicely, can mount it to your cordless drill. brownells or midway might even sell it, but you might see if you can see where the chamber is rough before going that far..just remember when polishing, oil oil oil Oil is your friend..and don't do any polishing which will bump up into the shoulder area, stay in the case body area..
 

Brain

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Re: Polishing up an AR-15 Chamber

If the case is truly stuck in the chamber and the extractor is working properly you should be seeing chunks of case rim being ripped off or seriously distorted.

Since the cases are easily removed via a cleaning rod down the bore, I would revisit the extractor before doing something irreversible to the chamber. Extractors and springs are cheap.
 

match308

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Re: Polishing up an AR-15 Chamber

Sounds more like a gas issue. Also reminds me of a CMMGs response to polymer coated Wolf ammo.
 

Captain Kirk

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Re: Polishing up an AR-15 Chamber

I think Greg Langelius (happy birthday Greg
wink.gif
) and 308sako are correct, I think its a pressure issue as well. I would try a TUBB CWS (carrier weight system) before going as far as polishing the chamber. The CWS will allow the bolt to stay locked longer, when the pressure spike goes down the bolt will open, and bring the spent case with it if all is well.

Kirk R
 

danr

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Re: Polishing up an AR-15 Chamber

I appreciate the feedback gents. First of all the weapon is a piston driven SR-556. I have it on the #2 setting as recommended by Ruger. Great rifle and accurate when it's working properly (which it usually does). This has happened approx. 8-10 times since I acquired it. I have about 1200 rds. thru it. I did change out the extractor/spring after the 5th or 6th failure, it ran fine then failed twice on my last outing. It could be one of several issues as stated by your responses. I think I will run factory 55 gr. ball for about 200 rounds to see if my ammo may be the cause. I know I'm not over-gassing the gun. My load is 24.2 grs. of Accurate 2230C and 55 gr fmjbt's. It is a safe load that does 3125 fps thru both of my 20" service rifles. It's my copy of military ball ammo that does 3200-3250 fps out of a 20" service rifle. It has been a reliable load (function/accuracy) for the past 20 yrs. or so. It may be I'm not getting the lube completely off the cases and gunking up the chamber as brought up with the polymer coated wolf ammo response. I really don't think this is the case as the ammo is slick and shiney when I handle it before placing it in it's container. A buddy recommeded I use a good solvent on the chamber brush, I usually just use BreakFree. I have fired my 69 gr. match load thru this rifle and it has been flawless in function and extremely accurate when I've topped it off with a scope. So the rifle has shown it likes bullet weights from 55-69 gr.'s with AA-2230C and W-748, powders I think most will agree have always been good .223/5.56 choices. I just need to pin down this one issue because I do think it is a great rifle.
 

Ren

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Re: Polishing up an AR-15 Chamber

When ever guys have problems with factory built AR's my response is always call the manufacturer and get them to fix it.

Unless your the 3rd or 4th owner, dont waste your time, waste theirs.


But....
If you just replaced the factory ejector spring with another factory ejector spring, it could still possibly not be enough. Try throwing an O ring around the spring also.
 

danr

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Re: Polishing up an AR-15 Chamber

Ruger allready sends them out with an O-ring
 

LongRifles Inc.

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    Re: Polishing up an AR-15 Chamber

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: danrodder</div><div class="ubbcode-body">Gent's, I have an AR that will sometimes fail to extract. The case will remain stuck in the chamber. The extractor is good as I replaced the original one but still does the same thing. The stuck case shows where the extractor claw had a good hold so I'm thinking I may have rough chamber. The stuck case will dislodge easily when I push it out with a cleaning rod. It is a factory rifle and it will fail to extract after cleaning with a chamber brush/solvent. My question is, Is there a tool readilly available where I can polish up the chamber myself to see if that takes care of it? </div></div>


    I haven't taken the time to skim over the other responses so forgive me if any of this is redundant.

    Extraction problems with AR's, M-4's, etc can often be traced back to an ammunition problem when the base components are in good working condition.

    Things off the top to verify about your rifle:

    Gas rings in good shape? a simple way to test is to extend the bolt as far as it'll go while in the bolt carrier. (out of battery position) Then sit it on a table. The rings should produce enough tension to support the carrier. Make a fist and wack the table. The carrier should now fall about 2/3 the way.

    If this is a carbine your extractor should have both a spring and a high durometer rubber "thingy". This increases the purchase tension on the rim of the case.

    Gas tube. If the tapered button feature on the end is worn or out of alignment it's going to reduce the charge/hang stuff up during cycling.

    Assuming this is all good its onto the ammunition.

    Ensure your using ammo with the right bullet weight. This most often results in failures to lock the bolt back or excessive pressure signs (flattened/smoked primers, etc) but I have seen it cause extraction problems too.

    Are your cases brass or the laquered up cheapo steel cases used by a few different "affordable" (code for garbage) ammunition manufacturers? If they are laquered and your shooting in any kind of warm weather it will begin to leave a funk on the inside of your chamber and cause a malfunction.

    Handloads. Are you full length resizing your cases? If so what dies are you using. Redding is awesome stuff BUT there are times I've seen "too much of a good thing". -Meaning they are one of the few companies that does not grossly oversize (in this case overly squish) the brass to ensure it will run in the chamber. In a bolt gun this is great because of the powerful forces at work. (camming action, powerful primary extraction, etc) In a gas gun it can mess with you. The RCBS dies are generally a bit smaller in size and although this works the brass more, it usually means it'll keep the gun running pretty decently.

    Combine the bigger dies with fat powder charges and I think we can see where extraction becomes an issue.

    Last, your chamber. The differences between 5.56mm Nato and 223 Remington are quite small and seemingly insignificant but they can be "annoying" at times. If your by chance shooting NATO M82 ball through a 223 chamber its possible to have extraction issues because the case pressures are going to elevate due to the smaller dimensions of the chamber. Essentially the case has less room for growth/relaxation and because the Nato round operates a bit more pressure than the 223 it can be a bit fussy when its time for it to come out.

    Last. Direct gas operating systems generate quite bit more heat in the base components than other types of semi auto rifles. It's not really anything to get overly concerned about as its a pretty reliable/simple system. The trick is to KEEP IT WET. Good ol CLP/Break Free is about the best stuff going for this. Grease and other forms of lubricant are great for high shear area parts like sears and whatnot, but for sliding parts experience in horrible environments has proven to me that making that thing borderline slobbery wet will keep that gun working.

    These are all things I experienced during a 3 year tour (2006-2009) in Iraq as the Chief Armorer and Chief Firearms instructor for the Baghdad Embassy Security Force under the U.S. Dept of State High Threat office. I worked that country from one end to the other servicing both American and Soviet designed weapon systems. They all love OIL.

    Good luck.


    Chad
     

    danr

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    Re: Polishing up an AR-15 Chamber

    No luck necessary Chad. What I need is more attention to detail and do a better job of inspecting my brass. I have been reloading it for quite awhile now and I can see how the extractor might fail on some of these case heads so I dumped all that old brass. I prepped/loaded 400 cases of once fired Winchester brass, went to the range yesterday and this morning, and my SR-556 went thru all 400 rds. without a single issue. Every round right thru the heart of my full size steel silhoutte, prone at 100 yds, squeezing them off as quick as I could settle the 4 moa dot. She's a good girl.

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