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Thread: Tons of bolt-over-base malfunctions...help

  1. #11
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    My other complete Noveske rifle suffered similar malfunctions, but only on reloads using the bolt-release with a full mag, once every 10-15 reloads or so. I think it's a geometry issue exacerbated by increased harmonics and BCG speeds. I will try the blue spring and make an H3 buffer.

    I think it's more of a leverage issue, as when the round hits the feed ramp, it is hitting it at a steeper angle, as well as having less contact with the bolt-face, it is likely much more possible it would "slip below the bolt-face", as it were as it noses up into the chamber (obviously tilting the rear down).
    Last edited by WS6; 11-27-13 at 01:02.

  2. #12
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    I would get another lower and then try it with this upper. Same ammo, mags, etc... if it doesn't happen then you know your issue. I have said this dozens of times and it bears repeating. In order to troubleshoot stuff you need to know where to start and you need to have equal parts of KNOWN functional origin so you can sort the issue. Otherwise you will be chasing your tail.

    On a side note: Is there no one comepetent in your area that could look at this? If you absolutely get stumped send the upper to me and I will look at it.

    Quote Originally Posted by WS6 View Post
    My other complete Noveske rifle suffered similar malfunctions, but only on reloads using the bolt-release with a full mag, once every 10-15 reloads or so. I think it's a geometry issue exacerbated by increased harmonics and BCG speeds. I will try the blue spring and make an H3 buffer.

    I think it's more of a leverage issue, as when the round hits the feed ramp, it is hitting it at a steeper angle, as well as having less contact with the bolt-face, it is likely much more possible it would "slip below the bolt-face", as it were as it noses up into the chamber (obviously tilting the rear down).



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  3. #13
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    Quote Originally Posted by Iraqgunz View Post
    I would get another lower and then try it with this upper. Same ammo, mags, etc... if it doesn't happen then you know your issue. I have said this dozens of times and it bears repeating. In order to troubleshoot stuff you need to know where to start and you need to have equal parts of KNOWN functional origin so you can sort the issue. Otherwise you will be chasing your tail.

    On a side note: Is there no one comepetent in your area that could look at this? If you absolutely get stumped send the upper to me and I will look at it.
    I don't personally trust that anyone in my area could do much good with it. Barry Dueck put a goodly amount of rounds downrange using my upper and did not report any problems except for a massive POI shift suppressed vs. unsuppressed. It was run on their MK18's, and other lowers.

    I will see what I can do with it, myself, but if I end up being stumped, I appreciate your offer and will take you up on it at that time. Thank-you very much!

  4. #14
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    Quote Originally Posted by Iraqgunz View Post
    I would get another lower and then try it with this upper. Same ammo, mags, etc... if it doesn't happen then you know your issue. I have said this dozens of times and it bears repeating. In order to troubleshoot stuff you need to know where to start and you need to have equal parts of KNOWN functional origin so you can sort the issue. Otherwise you will be chasing your tail.

    On a side note: Is there no one competent in your area that could look at this? If you absolutely get stumped send the upper to me and I will look at it.
    Sagely advice. I'd also recommend that you use a high quality ammunition to troubleshoot with. Contrary to their assertion, PMC does not stand for Precision Made Cartridges.

  5. #15
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    Bolt overs are a symptom of short stroking. It's also a symptom of a weak action spring
    INSIDE PLAN OF BOX
    1. ROAD-RUNNER LIFTS GLASS OF WATER- PULLING UP MATCH
    2. MATCH SCRATCHES ON MATCH-BOX
    3. MATCH LIGHTS FUSE TO TNT
    4. BOOM!
    5. HA-HA!!

    -WILE E. COYOTE, AUTHOR OF "EVERYTHING I NEEDED TO KNOW IN LIFE, I LEARNED FROM GOLDBERG & MURPHY"

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  6. #16
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    I reproduced the failure using an h2 and new milspec spring in an proven lower. It happened about mid-way through the mag.
    I was unable to reproduce it in the noveske lower using h3 and sprinco blue spring.
    It is not technically bolt over base. More like "stuck half way in the chamber". I took a picture. Will post soon. It tried to do it once on bolt release. I felt a two stage jump as it chambered, if that makes sense. Pictures when I'm home.
    Last edited by WS6; 11-27-13 at 13:33.

  7. #17
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    I believe the problem is a geometry issue with the upper. Slowly dry-cycling rounds shows that their tips impact the feed-ramp a bit lower than my Daniel Defense upper allows on my other rifle. Further, as soon as the bolt touches the back of the cartridge, it nose-dives and the magazine tips forward a bit. Considering that pressure on the mag prevents using the bolt-release, I think the lower may play a smaller role, as well. Here are the pictures of the failure in situ:



  8. #18
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    I've seen a NUMBER of Novekse lowers that the bolt catch shelf and the bolt catch itself is machined to high -- this causes excess drag on the bolt carrier and will result in what you are seeing.
    Kevin S. Boland
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  9. #19
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    Quote Originally Posted by KevinB View Post
    I've seen a NUMBER of Novekse lowers that the bolt catch shelf and the bolt catch itself is machined to high -- this causes excess drag on the bolt carrier and will result in what you are seeing.
    That particular jam, identical to the noveske lower jam, occurred on a dd lower. Fwiw.

  10. #20
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    Quote Originally Posted by WS6 View Post
    I was unable to reproduce it in the noveske lower using h3 and sprinco blue spring.
    That's good to hear!
    "I never learned from a man who agreed with me." Robert A. Heinlein

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