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Thread: CMMG LE 16" issue

  1. #1
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    Exclamation CMMG LE 16" issue

    Hey all

    I took one of my AR15's out to the range to sight in my irons and Eotech out to 50 yards.

    Scenario
    temp around 50 degrees
    Ammo PMC 55 grain bullets
    Carbine Gas System

    Never had this happen in the past with Russian ammo and Brass as well reloads.
    Magazines were C Product Mags with Magpul Follower and spring.


    shot a couple rounds to sight in which I had two failure to chamber.
    First mag after the first 3 shots the 4th round jams.
    I looked at the round and it was un-shootable. Round was slightly bent as well you can see were it looks like the BCG cut in and jam'd into the unfired casing.
    It seemed as if the bcg is not going back fully and you can see where it started to grab the outside of the casing and pushing it forward and cutting in till it got towards the feed rams and thats when you can see the BCG bending the round as well cutting into the brass.

    This happened 3 times with each round looking exactly the same far as damage that was done to the rounds.

    After I sighted the AR in I noticed my ejected casings from my spot were at between 12:00-1:30. I did noticed one flying up front when I saw it through my eotech when shooting earlier.

    I am not sure how to diagnose this. I checked my BCG and everything looked normal. The ejected casings looked normal. I have read somewhere that it could be from a over gas issue? but looking at the rounds that failed to feed looked like it could be from under gas issue?

    I have a ST-T2 buffer on the way for a build Iam doing I may throw that in and see if it fix's the issue or would it just put a band aid on the problem?

    Then again till I am waiting on it might as well try out the other spare BCG's I have laying around(2 PSA Auto BCG and 1 BCM)

    Any advise be appreciated since it seems like I have to opposing problems with the rifle.

  2. #2
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    I would try different mags, I have had nothing but bad experiences with c-products.

  3. #3
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    If I understand your description, it sounds like a bolt over. A bolt over is when the bolt passes over the top round in the magazine without picking it up. It shoves the case forward and partially out of the magazine, bending it.

    Bolt overs are usually due to short stroking which is from under-powered ammo, gas leakage in the system, blockages in the gas system, undersized gas ports or any combination of the above. If the BCG is dry, it can cause short stroking as well
    The number of folks on my Full Of Shit list grows everyday

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  4. #4
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    That sounds about right. I'll start checking for gas leaks. Gun was properly oiled with fire clean.

    Thanks for the responses.

  5. #5
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    I forgot to add that bolt overs can occur when the magazine presents the round too low, at the wrong angle or a combination of both
    The number of folks on my Full Of Shit list grows everyday

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  6. #6
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    Quote Originally Posted by dentron View Post
    I would try different mags, I have had nothing but bad experiences with c-products.
    Word...

  7. #7
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    cmmg + c-products = issues.

    Don't spend anymore money to fix the problem.

    Sell the cmmg and c-products mags and get a BCM, DD, Colt, LMT, etc. rifle plus Magpul PMags.

    Problem solved.

  8. #8
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    Quote Originally Posted by Singlestack Wonder View Post
    cmmg + c-products = issues.

    Don't spend anymore money to fix the problem.

    Sell the cmmg and c-products mags and get a BCM, DD, Colt, LMT, etc. rifle plus Magpul PMags.

    Problem solved.
    Or just sell the mags and get some pmags or quality metal mags. I have had problems with c-products mags in my cmmg m4le as well as my seekins/bcm. No problems with other mags in either rifle.

  9. #9
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    Just to double check another issue, I'd try and compare the magazine release against a known good lower. A lot less likely than any of the above, but the LPK's CMMG has sourced over the years vary from top notch to what seems like DPMS rejects.
    عندما تصبح الأسلحة محظورة, قد يملكون حظرون عندهم فقط
    کله چی سلاح منع شوی دی، یوازي غلوونکۍ یی به درلود
    Semper Fi
    "Being able to do the basics, on demand, takes practice. " - Sinister

  10. #10
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    I use the acronym MEAL to diagnose malfunctions in an AR - Magazines Ammo Extraction Lube...
    never push a wrench...

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