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Thread: Badly misaligned feed ramps on Colt upper... something to worry about?

  1. #31
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    Quote Originally Posted by recce556 View Post
    From my understanding, a factory built Colt upper will have a small proof mark on the upper next to delta ring on the ejection port side. Here's a pict on a A2 upper, in the mark closer to the ejection port door. On the M4 uppers, it should be in a similar location. Check both sides of your upper.

    Attachment 24625 Attachment 24626
    (Images from Urban_Ops from a post over at ARF)

    I've built over 100 uppers using individually sold Colt M4 uppers receivers (meaning not disassembled from complete uppers) and none of them had the VP ("Verified Proof" from a test fire) proof mark. All the factory built Colt uppers that I have (several) and upper receivers that I've built from "pull downs" all had VP proof marks.


    The only time they have proof marks is if they were apart of a factory complete gun or got factory proof fired. These proof marks began to disappear past 2002.

    An upper can lack proof marks and still be factory assembled and factory test fired.
    "Not every thing on Earth requires an aftermarket upgrade." demigod/markm

  2. #32
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    OP, How about taking another picture with the upper resting on it's sights so that everything is lined up vertically instead of the photo with the upper angled? Then you/us will get a better view of what is off kilter. If your BCG is locking up correctly as you stated, then as mentioned before, it's most likely the barrel extension is good and the M4 feed ramps are off. As Toddler stated, from your only photo it sure does look as if it's the receiver at fault. You can go to the range and test fire. If no problems occur, leave it alone and run with it.

  3. #33
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    Quote Originally Posted by scottryan View Post
    The only time they have proof marks is if they were apart of a factory complete gun or got factory proof fired. These proof marks began to disappear past 2002. An upper can lack proof marks and still be factory assembled and factory test fired.
    Ah, good to know, I knew you would be able to shed more light on that.

  4. #34
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    okay this isn't perfect but as far as I can tell it seems to be the upper
    Attached Images Attached Images

  5. #35
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    Quote Originally Posted by Hygienist View Post
    T
    I don't have a ton of experience on the AR15 platform, but based on a Colt AR15A4 I had for a bit (not any longer), the bolt seems to engage like it should. The bolt lugs go through the barrel extension just fine and the BCG shoves forward into place as it should.
    Ok. Then 95% it's just the upper receiver, the replacement of which is a relatively easy and fairly inexpensive undertaking.
    Jack Leuba
    Director, Military and Government Sales
    Knight's Armament Company
    jleuba@knightarmco.com

  6. #36
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    I'd get a BCM or MUR upper and swap it out.
    "You people have too much time on your hands." - scottryan

  7. #37
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    Looks like Colt should replace the receiver for you and get you one that lines up with the barrel extension. Personally I would exhaust that route before having to pay for a replacement receiver for a manufacturers goof.

  8. #38
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    Now that we have a better pic of the issue, I think a new upper would more than likely fix it. I would still return it to the guy who sold it to you unless you got such a good deal that you are willing to spend another 85.00 on an upper and parts.



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