Page 2 of 4 FirstFirst 1234 LastLast
Results 11 to 20 of 35

Thread: Canted FSB or out of spec upper ?

  1. #11
    Join Date
    Dec 2007
    Location
    Sparr, Florida
    Posts
    482
    Feedback Score
    1 (100%)
    If you have a carrying handle laying around put it on the upper. Then turn the whole thing upside down and see if there are four points of contact. Also make sure what you place it on is flat and true. If there isn't then there is a problem. On a brand new upper you should have all four points touching within a few sheets of paper. Also when you set the upper down flat how does the front sight base look? You paid money for it so it should be right.

    Dan
    Support your local Deputy.

    It is better to sweat in Training than Bleed in Battle.


    www.usnst.org

  2. #12
    Join Date
    Oct 2007
    Posts
    313
    Feedback Score
    0
    Call BCM and tell them your problem and ask them to repair or replace. I'd bet you have an RMA# shortly and they swap out the upper. Who knows, you might have the first of a bad batch that made it out the door and needs to be stopped from being sold. Let them know ASAP so the problem can get resolved.

  3. #13
    Join Date
    Aug 2010
    Location
    out west
    Posts
    93
    Feedback Score
    0
    Had a similar experience with my BCM midlength, BUIS looks similar, the Aimpoint required considerable adjustment also. I think there are several threads concerning this issue with BCM middies. Looks like a QC issue to me.

  4. #14
    Join Date
    Mar 2012
    Posts
    44
    Feedback Score
    0
    When I took my Aimpoint off my other upper (the same upper that had the Troy BUIS) it took 24 clicks to the left and 24 click down to hit the point of aim.

  5. #15
    Join Date
    Sep 2008
    Location
    Texas
    Posts
    1,316
    Feedback Score
    33 (100%)
    Wow, 2 in a row.

  6. #16
    Join Date
    Dec 2011
    Location
    East Tennessee
    Posts
    1,225
    Feedback Score
    10 (100%)
    All this "crooked mid-length" stuff has me a little spooked. Mine just arrived last week and has yet to be fired. I flipped it upside down on the table and it's a little off, but not much. I boresighted it out the window (~25m) and it's close to mechanical zero, so I think it's fine. It may be a little while before I can get it out to the range and on the bench.. Ron
    Ain't no pockets on a shroud..

  7. #17
    Join Date
    Mar 2012
    Posts
    44
    Feedback Score
    0
    Quote Originally Posted by SW-Shooter View Post
    Wow, 2 in a row.
    what was the other one?

  8. #18
    Join Date
    Mar 2010
    Location
    AZ
    Posts
    186
    Feedback Score
    1 (100%)
    Some of you guys must have some expensive kitchens to trust the flatness of your tabletop to determine if your upper assemblies are square.

    OP, front sight posts are relatively easy to visually inspect if they're straight or not. I've had a couple FSB come crooked from a particular manufacturer (not BCM) and it was readily apparent by visual inspection.

    If the FSB appears straight, and you have the experience/ability & tools to assemble uppers, you might consider removing the barrel nut & barrel from the receiver and simply re-installing. Same with your rear sight. You never know...

  9. #19
    Join Date
    Jan 2012
    Posts
    694
    Feedback Score
    11 (100%)
    Quote Originally Posted by 2arkba View Post
    what was the other one?

    SW-Shooter is on some big crusade to say that BCM is no better than DPMS, Olympic Arms, etc.

    Seems to me perhaps BCM got a bad batch of upper receivers. This problem has been reported a lot lately. In all honesty, it's small potatoes in comparison to the problems companies like DPMS and RRA see buddy.
    Last edited by djmorris; 05-07-12 at 08:26.

  10. #20
    Join Date
    Nov 2010
    Location
    Iraq
    Posts
    489
    Feedback Score
    2 (100%)
    Quote Originally Posted by 2arkba View Post
    When I took my Aimpoint off my other upper (the same upper that had the Troy BUIS) it took 24 clicks to the left and 24 click down to hit the point of aim.
    In that case, my money is on my point made in post #9 being the "issue", rather than a canted FSB. But I still hold the fact you can zero it means its not really a big deal. Even with two rifles that are completely true, you will have to re-zero an optic to some degree when moving it from one rifle to another.

    If you want to try for perfection, remove the barrel and lap the upper receiver face using this sort of tool:

    http://www.brownells.com/.aspx/pid=2...R-LAPPING-TOOL
    Dan

Page 2 of 4 FirstFirst 1234 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
  •