Page 1 of 2 12 LastLast
Results 1 to 10 of 13

Thread: Help Diagnose My 11.5 SBR

  1. #1
    Join Date
    Aug 2008
    Posts
    233
    Feedback Score
    0

    Help Diagnose My 11.5 SBR

    The upper is a complete BCM 11.5in upper running a DD bolt, lower is a G&R built BCM lower. I changed the receiver extension to the Vltor A5 and have tested both A5A3 buffers, as well as the standard A5 buffer. Both have this issue. am having the following issue every few rounds:



    It almost looks like a double-feed, but it's actually that the previous round is failing to completely extract and the live round is feeding under it.

    I've tried multiple magazines, all exhibit the same issue.

    The fired brass is indented as pictured below, but I didn't know if that was a symptom of the case getting slammed together, or related to whatever is the root cause.



    Curious as to what would be the next test to run:
    1) Test a different Complete BCG.
    2) Test lower against my 16in BCM mid-length upper that runs fine on an identical lower that I have.
    3) Something else?

  2. #2
    Join Date
    Jan 2008
    Location
    AZ-Waging jihad against crappy AR's.
    Posts
    24,900
    Feedback Score
    104 (100%)
    Are you using an O-ring? How many rounds are on the extractor?



    Owner/Instructor at Semper Paratus Arms

    Facebook: https://www.facebook.com/SemperParatusArms/

    Semper Paratus Arms AR15 Armorer Course http://www.semperparatusarms.com/cou...-registration/

    M4C Misc. Training and Course Announcements- http://www.m4carbine.net/forumdisplay.php?f=141

    Master Armorer/R&D at SIONICS Weapon Systems- http://sionicsweaponsystems.com

  3. #3
    Join Date
    Feb 2009
    Location
    30802
    Posts
    158
    Feedback Score
    0
    Do you have another bolt to try ? Agree, oring ?

  4. #4
    Join Date
    Dec 2010
    Posts
    1,106
    Feedback Score
    66 (100%)
    Could this be due to a weak ejector spring?
    "To preserve liberty, it is essential that the whole body of people always possess arms..."
    - Richard Henry Lee, 1788

  5. #5
    Join Date
    Jan 2008
    Location
    AZ-Waging jihad against crappy AR's.
    Posts
    24,900
    Feedback Score
    104 (100%)
    I wouldn't rule it out. I would check the extractor first and then the ejector. If you can easily push it down or it is mushy then it needs to be replaced.

    Quote Originally Posted by NoveskeFan View Post
    Could this be due to a weak ejector spring?



    Owner/Instructor at Semper Paratus Arms

    Facebook: https://www.facebook.com/SemperParatusArms/

    Semper Paratus Arms AR15 Armorer Course http://www.semperparatusarms.com/cou...-registration/

    M4C Misc. Training and Course Announcements- http://www.m4carbine.net/forumdisplay.php?f=141

    Master Armorer/R&D at SIONICS Weapon Systems- http://sionicsweaponsystems.com

  6. #6
    Join Date
    Mar 2011
    Posts
    2,511
    Feedback Score
    1 (100%)
    Quote Originally Posted by NoveskeFan View Post
    Could this be due to a weak ejector spring?
    Or not enough lube. I had the same problem with my 11.5, put a bunch of lube on the ejector and worked up and down with a spent casing. Been working fine now.
    Last edited by Inkslinger; 10-23-12 at 05:17.

  7. #7
    Join Date
    Jan 2012
    Posts
    965
    Feedback Score
    24 (100%)
    Good info here

  8. #8
    Join Date
    Feb 2011
    Posts
    2,513
    Feedback Score
    82 (100%)
    OP

    You stated you changed the RE out for the Vltor A5. Prior to doing this did you have this same problem with the original RE?

    I would assume it was a standard carbine length RE?

  9. #9
    Join Date
    Aug 2008
    Posts
    233
    Feedback Score
    0
    Quote Originally Posted by davidjinks View Post
    OP

    You stated you changed the RE out for the Vltor A5. Prior to doing this did you have this same problem with the original RE?

    I would assume it was a standard carbine length RE?
    No, I ordered the Lower without a carbine extension.

  10. #10
    Join Date
    May 2011
    Posts
    3,095
    Feedback Score
    7 (89%)
    What ammo?
    Quote Originally Posted by C4IGrant View Post
    Colt builds War Horses, not show ponies.
    Quote Originally Posted by Iraqgunz View Post
    This is 2012. The world is going to end this December and people are still trying to debate the merits of piece of shit, cost cutting crap AR's. Really?

Page 1 of 2 12 LastLast

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •