Various misfeed issues
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Thread: Various misfeed issues

  1. #1
    Newbie Kringus's Avatar
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    Various misfeed issues

    From my search of the site I believe I have a bad gas block/dial/regulator. However I am curious if you all concur. I have a 5.56 mm 16" XCR L with a a 46XX SN.
    I purchased it NIB in June of 09. It has never fired steel ammo well but brass was ok. Now brass ammo is failing to extract, eject, and double feed. The weapon to include the gas block was cleaned prior to firing. After shooting I can see a bit of brass shavings throughout the upper and some on the lower receivers I am using Federal T556TNB1. I just sent an email to Robarms detailing the malfunctions.



    ETA gas settings 3 and 4.
    Attached Thumbnails Attached Thumbnails Various misfeed issues-20120624.jpg   Various misfeed issues-20120624.jpg  

  2. #2
    Expert TEXAS SOLFTAIL's Avatar
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    Re: Various misfeed issues

    What gas setting are you on?

  3. #3
    XCR Guru Sean K.'s Avatar
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    Re: Various misfeed issues

    Guessing it's several issues.....probably out of spec gas port sizes in the block and bbl (possibly the dial) and a tight chamber. I base that on the serial number. I was in the 3300-3700 range and those were SOME of my issues. ***EDIT***Sorry.....I transfixed the serial numbers.....mine are older than yours is....I've corrected the numbers above****

    Also had an improperly welded (crooked) op-rod to the foot that mates to the carrier which caused drag in the entire system, slowing the bolt/carrier enough to short stroke the gun with steel case ammo.

    Do a search for port sizes and use a new set of drill bits (yes, gauge pins would be more accurate) to check the port sizes.

    Flip your upper upside down and drag the carrier/bolt out of the upper via the recoil spring/latch assembly.....if the op rod is hanging up or meeting resistance before the carrier is out of the upper....enough resistance that the spring/latch assembly pull out before the carrier.....then you likely have a crooked foot welded to the op rod.

    As for why it's happening after what I'm assuming to be a lot of rounds.....probably a dirty chamber.....a hone will likely clean up and clear up your problem entirely....I'd recommend the 400 grit personally from brush research.com. Runs about $50 with their honing oil. A simple good scrubbing/soaking with Hoppe's or similar may also clear up your issue.....so you may want to try that first.

    If it were my gun, even if that solved the problem, I'd want to be sure it ran anything, which means buying some shit Tula or Wolf and see what happens.....fix the gun til it runs on anything even if you choose (or aren't able) NOT to clean it for 1K rounds. Once you get that kind of reliability out of your XCR, you'll have a lot more faith in it.


    JME,

    Sean
    "Necessity is the plea for every infringement of human liberty. It is the argument of tyrants; the creed of slaves."-William Pitt the Younger

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  5. #4
    XCR Guru BuddyChryst's Avatar
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    Re: Various misfeed issues

    First, when was the last time you cleaned the rifle, and did you clean the gas dial and chamber?

    Second, the rounds in the picture...what's the story behind each one?

    The dented case looks like an ejected case on too high of a gas setting. The two with bullet setback look like double feeds and the dented one looks like a short stroke or tight magazine feed lips. IMO, I see several problems, some possibly contradictory. I see symptoms of too high of gas, and also too low, or a magazine problem.

    I don't see any signs of stuck cases (bent/ripped rims) in those pictures. Did you notice any?

    When the rifle does extract and eject, what's the pattern? What position do the cases eject to and how far do they go?

    Are you using different magazines? What kind of mags? Do they happen with all mags? If you're using just the metal mag that came with the rifle, I'd ditch it and try pmags. I had similar problems with my original mag and ended up blasting it full of holes. I only use pmags now and have no problems.
    Charter member of the vast, right-wing conspiracy

  6. #5
    Newbie Kringus's Avatar
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    Re: Various misfeed issues

    First, when was the last time you cleaned the rifle, and did you clean the gas dial and chamber?

    Cleaned the whole weapon two weeks prior to shooting. I let the dial soak overnight in CLP.

    Second, the rounds in the picture...what's the story behind each one?

    All of them except one, are rounds that the weapon tried to load after an FTE. I.E. there was an expended case in the chamber and those rounds impacted against the case in the chamber.

    The round with the chewed up neck was caught between the bolt and the ejection port as it was extracted.


    The dented case looks like an ejected case on too high of a gas setting. The two with bullet setback look like double feeds and the dented one looks like a short stroke or tight magazine feed lips. IMO, I see several problems, some possibly contradictory. I see symptoms of too high of gas, and also too low, or a magazine problem.

    I am using PMAGs. I have several with the black followers and I purchased two new ones with gray followers that day. Also I used a Surefire 100 rnd mag. I experienced malfunctions with all of them. I fired mostly on setting 3 and switched to 4 but still got FTEs.

    I don't see any signs of stuck cases (bent/ripped rims) in those pictures. Did you notice any?

    No

    When the rifle does extract and eject, what's the pattern? What position do the cases eject to and how far do they go?

    Ejection is at 3 going about 10 feet.

    Are you using different magazines? What kind of mags? Do they happen with all mags? If you're using just the metal mag that came with the rifle, I'd ditch it and try pmags. I had similar problems with my original mag and ended up blasting it full of holes. I only use pmags now and have no problems.


    Pmags black and gray followers, and a surefire 100rnd mag.

    Thanks everybody for the replies and help.

  7. #6
    XCR Guru Carpenter's Avatar
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    Re: Various misfeed issues

    If you are FTE without munched rims, could it be worth a look at your extractor?
    hope for the best, prepare for the worst, and make hay while the sun shines!

  8. #7
    XCR Guru Sean K.'s Avatar
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    Re: Various misfeed issues

    Quote Originally Posted by celiajean View Post
    If you are FTE without munched rims, could it be worth a look at your extractor?
    There's a measurement for the edge of the firing pin hole to the outside flat on the extractor I've posted in the past.....search for it and ensure it's right.....but I doubt that's it though.

    Mags would cause a feed issue....but the FTE's are likely a tight/rough/dirty chamber and a shortage of gas.

    CLP isn't much of a solvent. Even overnight, it won't remove really built up carbon deposits without serious scrubbing. Check the dial holes themselves and make sure they are cleaned out. Also, check to be sure your gas block is tight...if gas is leaking around the block, then the action may not be getting enough gas.....just tighten the allen screw in the bottom to be sure.

    HTH,
    Sean

    "Necessity is the plea for every infringement of human liberty. It is the argument of tyrants; the creed of slaves."-William Pitt the Younger

  9. #8
    XCR Guru Sean K.'s Avatar
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    Re: Various misfeed issues

    Quote Originally Posted by celiajean View Post
    If you are FTE without munched rims, could it be worth a look at your extractor?
    For the record, I had FTEs without the rim having much more than some swipes on them.....but, this was with steel cased ammo....JFYI. Actually, none of my FTEs that I looked at where a case was stuck in the chamber showed that the extractor had seriously mangled the rim. At most, I had a few nicks in the edge where the extractor had slipped off.....and I mic'd all of the extractors on my bolts and spare bolts to make sure they were in spec.

    Sean
    "Necessity is the plea for every infringement of human liberty. It is the argument of tyrants; the creed of slaves."-William Pitt the Younger

  10. #9
    XCR Guru BuddyChryst's Avatar
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    Re: Various misfeed issues

    Okay, I think it's safe to say we can eliminate mags as contributing to the problem (although I'm always suspicious of 100 rounders).

    Now I'd look at the gas system and extractor. I don't know much about extractors, so I won't be much help there. Do you have any caliber conversions where you might accidentally have the wrong bolt installed? Can you cycle rounds by hand and have them extract and eject? If so, I'd probably rule out the extractor.

    For the gas system, something has gotta be going on there. On setting 3-4 with brass you should be chucking it 20+ feet at least. Let's start with the easy part. Checking the dial. Even with a good soak, the dial probably needs to be scrubbed. Make sure all the holes are clear. Also check to make sure the dial is stamped with the correct settings. My 7.62x39 dial has the numbers stamped wrong...they don't correctly correlate to the gas holes. The proper alignment should be the smallest hole pointed down to the barrel should have the S at the detent. The biggest hole facing down should have the 4 at the detent.

    Next is looking at the gas block. Make sure the block is indexed properly and tight so you're not losing gas. Again here I'm not so educated, so others may be able to help more.

    The last thing to look at is the chamber. Make sure to use a chamber brush to clean it. If I remember correctly, a .40 brush is about the same size. Someone may correct me if I'm wrong. It's possible you have a tight chamber, but I would think that would've been apparent right away, not after working fine to start. So it could be rough and/or dirty. People have reported great success with flex honing the chamber, but I wouldn't trust myself to do it. I'd hate to do too much.
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  11. #10
    Newbie Kringus's Avatar
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    Re: Various misfeed issues

    No caliber conversions. I have not really fired the weapon a lot since the break in. I have maybe 1200-2000 rounds through it. Mostly wolf for plinking. When the wolf failed I just chalked it up to bad ammo.

    I will be getting some hoppes 9 for the chamber and the gas block/dial and shoot it again. The dial holes align with the correct numbers. I checked the block and it is tight on the barrel.

    The BCG comes out when I had the receiver upside down. At least when I pull on it slowly. Faster and the spring starts to come out of the BCG. But I will try again once I clean it up with the hoppes.

    Thanks everybody for your suggestions. I really appreciate it.

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