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AR Malfunction - Please help diagnose

Discussion in 'Rifle Country' started by azrocks, Oct 20, 2016.

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  1. MistWolf

    MistWolf Member

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    Replace your extractor spring. Get the copper colored Colt spring with the black rubber insert. DO NOT use an O ring. Midway had them in stock last week for about $5 or $6. You might also replace the extractor as cheap insurance and check the ejector while you're at it. Pull the bolt, place an empty in the bolt face and let the case fly. It should zip across the room. If not, replace the ejector spring
     
  2. rjrivero

    rjrivero Member

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    This picture is definitely a short stroke. That round is definitely not American Eagle XM 193. That's a lacquered bullet, brown bear or some other commie block ammo which is notoriously under powered. More than likely your gun is fine and will chew up quality bulk ammo without issue.
     
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  3. MistWolf

    MistWolf Member

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    If the rifle were short stroking, it would not lock back on an empty mag
     
  4. C-grunt

    C-grunt Member

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    Do you have anything from them saying that?

    Their lowers all come with H buffers.
     
  5. MrCleanOK

    MrCleanOK Member

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    What you're getting is called a bolt-over-base failure to feed. That's caused by one of two things; short stroking causing the bolt to not clear the back of the new cartridge before returning to battery, or excessive bolt speed or weak magazine springs causing the bolt to outrun the magazine's ability to shove a new round up into its path.

    Try the easiest fix to the easiest problem first. Assume it's short stroking (I think it probably is) and use more lube. The brief description of your lube schedule in your initial post leads me to believe your rifle is on the dry side. Rem Oil is a fine lube, but not for AR-15s. It evaporates too quickly. Your Break Free will do the job, just use more of it. There is no such thing as too much lube, it's a self-correcting problem. If you put too much in there, the rifle will just blow the excess out the first time you pull the trigger.
     
  6. wally

    wally Member

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    Not strictly true, there is extra friction on the carrier from the rounds in the magazine. The maximum friction is usually somewhere in the first half of the capacity and is almost assuredly minimum after the last round has been chambered.

    If you go the "no such thing as too much lube" route, be sure to wear safety glasses and an old shirt :)
     
  7. tark

    tark Member

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    This may sound a bit odd....but that round of ammo in the pic looks a bit odd.. It looks very much like a 5.45X39 . The shoulder is too long to be an M-193. I have never seen red lacquer on a federal M-193 bullet. The odd color of the case and that red lacquer matches the 5.45X39 Soviet military rounds exactly. That is a steel case, I'm guessing. If I'm right, it is very obvious why things didn't work.

    But I'm probably wrong. Lately, there has been an alarming increase in the number of things about which I know Nothing.
     
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  8. MrCleanOK

    MrCleanOK Member

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    Folks seem to not be reading close enough. That's just a picture of a similar malfunction that the OP found on the internet. It's not his rifle or his ammo. He said what ammo he was using, and it's not weak steel cased stuff.
     
  9. mjsdwash

    mjsdwash Member

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    ]But the thing I can't understand is that if this was the case, why would the problem be intermittent, with most of the rounds chambering fine? And I'd think that as a rifle heats up, if anything more gas pressure would develop. -Yup, you would think, as did I, thats what got my attention, the similarities between what you describe, and mine. Still not sure what was going on, but after a new gasblock, that rifle has ran perfect. Thousands of rounds without issue, so it was not a bolt or building problem. I figured the block was drilled badly, eclipsing the gas hole, and expanded when hot, just covering it enough to act up. It was a properly pinned A2 site too.
     
  10. mjsdwash

    mjsdwash Member

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    Pretty normal for leakage. The Ar does not use a press on block, and uses a pinned gas tube, and is very constricted, and is not vented. Its not a great seal, and not vented until several inches down, so leaking will occur. Its supposed eventually clog up, and not leak again, but before that, it should still be cycling fully. IMO 'break in periods' are something gun makers throw out knowing most people will never shoot a firearm enough to 'break it in', and wont bother sending it back, because they just havent 'broken it in'- just a side note. If its leaking bad enough to be blowing visible soot out, or you can feel it on you hand that may be an issue, but some carbon deposited around the block and tube is normal.
     
  11. mjsdwash

    mjsdwash Member

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    know anyone with a lighter buffer? Is wont fix the issue, but may be good enough to get it going. It looks like you 90% there, maybe an ounce off would help? I
     
  12. MistWolf

    MistWolf Member

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    Negative. If the rifle were short stroking, it would not lock back on the last round. Period. What is happening is the extractor is losing control of the empty due to a weak extractor spring. Normally, it does so in a fashion that an empty case gets stuck inside the action along with the fresh round from the mag. In this case, the empty is staying in the action just long enough to prevent positive feeding but still manages to be ejected.

    If it's not the extractor spring, it's weak ejection or the case is getting hung up in the extractor.

    It is not short stroking. Using an adjustable gas block, the gas flow can be closed down until the rifle will eject the empty every shot from a full magazine without locking back on the last shot. When tuned this way, the rifle will not start malfunctioning in the manner described. Closing of the gas further will result in the rifle short stroking which MIGHT cause this type of malfunction, but the rifle will not cycle far enough to lock back on an empty mag.

    Every time I've experienced this malfunction with an AR, it's been a worn out extractor spring. Every time.

    AZ, try the easy fix first. Shoot the rifle with a bolt known to have a good extractor spring and good ejection. Your problem will go away. Replace the extractor spring with a Colt copper colored extractor spring with black insert for best results
     
    Last edited: Oct 22, 2016
  13. RussellC

    RussellC Member

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    Must be catchy...I have the same issue! Re: about knowing nothing lol!

    Russellc
     
  14. RussellC

    RussellC Member

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    Just get another bolt (always good to have spare parts) and try it. If that's it, buy some bolt rebuilding parts.

    I have never used the above mentioned Colt springs, will have to get some. I have used the BCM spring, insert and O ring. I like to never got it squished together enough to get the pin through! They also stood a little taller than the replacement....tough springs, these!

    I hope they work
    Russellc
     
  15. carbine85

    carbine85 Member

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    What you are describing is a Fail to Feed magazine related issue. Clean it, lube it, change the mag and try again.
     
  16. RussellC

    RussellC Member

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    He said it was a pic he found on the net showing his problem, not his gun....

    Russellc
     
  17. Coal Dragger

    Coal Dragger Member

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    Step 1.) Use a proper lubricant. Rem Oil is barely any better than mineral spirits. CLP or a heavier oil will stay put. Use lots of oil, as mentioned the rifle will blow off excess.

    Step 2.) Number your magazines. Take a note book to the range and record any malfunctions and note the magazine number.

    Step 3.) Try a different lot of good quality full powered NATO spec ammo in addition to the ammo that has been giving you issues.

    Step 4.) Test fire the cleaned and now properly lubed rifle with all your numbered magazines, and both types of good ammo. Record the ammo type and magazine number of any malfunctions.

    Step 5.) If function is 100% after changing lubrication, then you are good to go. Drink a beer to celebrate, and toss the Rem Oil in your tool box for lubing pliers which is all it's good for.

    Step 6.) If function is compromised with only the original ammo that was giving you issues, then you can no longer count on that ammo.

    Step 7.) If function is compromised with only certain magazines then those magazines are trashed and should be sent back to Brownell's for replacement.

    Step 8.) If function is compromised with both types of ammo, and all magazines then frankly it's time for the carbine to take a trip to BCM to get fixed if it is under warranty.

    Step 9.) If the carbine is not under warranty, then further self diagnostic efforts will be in order. Mist Wolf's advice on the extractor spring and extractor may be a good place to start in that case.

    My guess is that using proper lube, generously, and trying a newer lot of full power ammo will most likely clear this up.
     
  18. hdwhit

    hdwhit Member

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    The fact you shot 60 rounds without any problems and then this problem suddenly developed and occurred with different magazines suggests that it is not a problem with the magazines as it is unlikely that multiple magazines would all function properly and then all suddenly develop the same problem.

    The fact you shot 60 rounds without any problems and then this problem suddenly developed also suggests that it is not an issue with the buffer or the buffer spring (although it wouldn't hurt to carefully inspect both parts) as it is unlikely the buffer would have significantly changed weight or the spring's rate changed suddenly absent a catastrophic failure that would be immediately noticed during a visual inspection.

    I concur with the other posters who have said that what you described (and what is represented in the stock picture) is "short cycling" and would suggest that you focus your attention on the gas system. Look for leaks, blockages, damage to the gas tube, damage to or movement of the gas block, loosening of the gas key as well as any lubricants that may have (for want of a better term) been "caramelized" by the propellant gasses.

    When I was in the Army, we were given things that looked like long pipe cleaners to clean out the gas tube. Vietnam was already over by then, but the ammunition we were firing was made during the war years and the powder was particularly dirty. You can probably find long pipe cleaners at a craft or party supply store (or on the internet) to swab out the gas tube. You might also try blowing it out with compressed air.
     
  19. wally

    wally Member

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    Maybe, maybe not, the key issue is if the bolt is pushing the base of the cartridge or someplace else on the body. I've never seen one stop while pushing on the base of the cartridge unless the empty is is still in the port somewhere. The photo example (not the OP's gun, but he said its an example of what his looked like, despite it not being 5.56) is clearly not pushing on the base of the cartridge.

    If some significant fraction of his stoppages had the empty still in the port then I'd say you've got it, but if none are its either a gas issue or some mechanical issue in the magazines or upper. Long shot, but I had a friend assemble his without screwing the buffer tube in far enough to hold the buffer retainer pin and the mangled pin and its spring caused all manner of stoppages.
     
  20. azrocks

    azrocks Member

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    Lots of great information here guys! Sorry for not being around to answer/address questions or review potential solutions. Had a week of computer trouble.

    I'll try to take one thing at a time. A lot to catch up with so if I don't mention you by name know your advice is greatly appreciated.

    First, to clear up a couple things:

    1) The picture is not my rifle, nor is the ammo show what I was running. I just found this pic on the internet as it showed exactly what was happening.
    2) I do not know if the rifle would lock back on an empty mag consistently. For one, I kept topping my mags off. Second - since the problem was intermittent - even the couple times I did run dry don't mean anything since I was having more 'good' rounds than malfunctions.
    3) I've put at least 1000 and probably many more rounds through with this exact same ammo (same lot), same buffer, etc. So I think its safe to say buffer weight is not the problem. I'm reluctant to change the buffer to address a problem that I'm sure is caused by something else, unless the temporary switch would serve to help diagnose the issue.
    4) it is definitely not a problem with assembly.

    As far as mags go - I can't 100% rule out the possibility - but to my mind they're about the least likely possibility. As stated, this happened with multiple mags, which ran fine until the 60-round mark. I was using one 20-round for me, one 20-round for the wife, and had another 30-round for me shooting unsupported. We had no problems with any of them until the issue manifested for the first time, then we started having problems with all of them. Granted, 60 rounds isn't exactly statistically significant, but combined with the new condition of the mags, their pristine condition, and my thorough inspection & testing of all 3 after the incident, I'm fairly certain they're not the problem. I've used these same mags or those exactly like them up till now - as with the ammo - with zero malfunctions.

    I have inspected the gas system as much as possible visually. Sounds like the minimal leakage I'm seeing around the gas tube at the block is normal. In all other respects everything checks out fine. It appears secure, aligns well, does not appear to be obstructed (blew air through it with my mouth using rubber tubing over the gas tube, and also looked down it with a light), the gas key is secure, gas rings are gtg, etc. So I think I can rule out that potential issue as well. I have not cleaned the gas tube (ever), because it was my understanding that it was essentially self-cleaning due to gas pressure, and using things like pipe cleaners introduced more of a potential to clog it than carbon would. Whether this is true or not I don't know, but again physical inspection shows it to be fine, and I wouldn't expect <2000 rounds of clean ammo to be enough to gum it up anyway.

    No way I can rule out ammo for certain, but I think the nature of the problem suggests otherwise. It ran fine for 60 rounds of the same ammo I've been running for a while now, then started malfunctioning every 5 or so rounds. The sudden onset would seem to suggest ammo is not the issue, so I'm putting it in with magazines as 'possible but highly unlikely'

    So thanks to your help, I think its narrowed down to:

    1) Lube
    2) The extractor spring

    Now that I've examined everything, I must admit the bolt assembly looks a little dry. I'm going to follow yalls suggestion here and run it wetter next time. Is a good coating of CLP the best I can do, or would another lube be preferable? How about mobil1 motor oil?

    I do have another bolt available, but I'd rather isolate one thing at a time, so if the lube doesn't work I'll take its extractor spring and swap it out with the one in my current bolt assembly.

    And I'll bring different ammo just in case. And number my mags :)
     
  21. ny32182

    ny32182 Member

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    I did have an extractor spring go bad at about that same round count recently, but it manifested as failures to extract... the extractor was completely slipping off the rim and failing to eject. It was also obviously loose when handling the bolt out of the gun. Replaced everything under the extractor and it was fixed.

    It also sat for several years right before that happened.
     
  22. Coal Dragger

    Coal Dragger Member

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    CLP will work fine. Not to be a know it all, but I suggest running through the diagnostic list I posted to systematically rule out your components. I do suspect that proper lubrication will solve the issue, but run through everything anyway.

    Like you said... first 60 rounds ran fine. After 60 rounds down the pipe you're going to have some carbon build up, which is no big deal if your lubricant is still present and doing its job of lubricating the action. The lube will easily handle a lot of carbon, floating it in the lube. Ever noticed that a well oiled gun is often easier to clean? That's because the oil keeps the carbon fouling loose and fluid in the oil.

    Now if your oil is too light, and runs out, is blown out, or evaporates away it does no good. Rem Oil is not a heavy duty gun oil, in fact I'm not sure if it is even suitable for lubricating any auto loading firearm. I have no doubt 60 rounds of 5.56mm will blast every bit of Rem Oil out, and dry up any that doesn't blow out.

    CLP will not evaporate away or be so easily blown out. Other lubricants that I have had good luck with are: MPro 7 weapons lube, Shooters Choice FP-10, Miltec, and yes even motor oil.

    On the bolt itself I generously lube the locking lugs, bolt body, and gas rings. I put one drop of oil in the ejector. On the bolt carrier I generously lube the inside of the carrier, and the cam pin guide. On the exterior I also generously lube the carrier rails, and usually leave a light coat of oil on the phosphate finish of the bolt carrier body. The firing pin should get a light coat of oil.

    If you want to you can also lube the inside of the upper where the carrier rails reciprocate.

    AR's like to run wet! You'd be shocked how dirty they can be and work 100% so long as they have plenty of lube.
     
  23. azrocks

    azrocks Member

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    Think... harder...
    It's solid advice, Coal. Advice that if I had followed before problems began would have made initial diagnoses much easier, so I appreciate it greatly, and don't consider you or the others (243winxb) that said the same to be coming off as 'know-it-alls'. Consider it done.

    Thank you badkarmamib, Coal Dragger, ny32182, MistWolf, mjsdwash, MrCleanOK, wally, C-grunt, 243winxb, rjrivero, RussellC, and even the cryptic Varminterror! (plus anyone I may have missed)! Your input is GREATLY appreciated.

    I predict coming back on here after this weekend feeling very stupid when I (most likely) will be forced to admit I was running her dry, but maybe I'll find a 'real' malfunction after-all so I don't feel like a complete arse :)

    I'll report back Monday.
     
  24. kwg020

    kwg020 Member

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    Don't forget to lube your recoil spring in the tube. DO NOT use heavy grease in the tube as it will slow down the buffer. I understand 0 weight synthetic oil is about the right weight to run in the AR so get something similar. CLP will work but I'm not a fan of it. Someone said it before: number your magazines and eliminate the problem children. Go from there.
     
  25. azrocks

    azrocks Member

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    I'm a dummy...

    Adequate lube and she's back to running like a champ.

    I'm really wondering now if I might have had a brain fart the last time I put her back together. I usually left her fairly wet (compared to handguns) and only used rem-oil in certain spots. I'm thinking I might have got distracted halfway through the cleaning process. Anyway, I'm squared away now. Thanks all!
     
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