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Thread: A day in the life of a BM LE Dealer

  1. #1
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    A day in the life of a BM LE Dealer

    As many know, I recently received my BM LE account. Well today I got my first shipment of their super light carbines. (http://www.bushmaster.com/catalog_xm15_BCWA3F16SL.asp)

    Since this is my first order, I thought I would take the time to document what I found.

    On initial inspection, the weapon looked very good and clean. No dings, scratches or blems. I did notice two things though, the castle nut was NOT staked and the FSB was not F marked. Upon field stripping the gun, I found that the gas key was barely staked (meaning that that the stakes were not actually touching the screws) and that the screws used in the gas key were on the small size (head diameter was undersized). This issue can result in a gas leakage problem. I then removed the extractor from the bolt and found a blue extractor insert.
    The gun came with M4 feed ramps, carbine buffer and a commercial receiver extension.

    Un-staked Castle Nut


    Poorly staked Gas Key


    Blue extractor insert, no Crane O-ring


    M4 Barrel extension and M4 upper receiver



    The small gas key screws really needed to be addressed so I went about removing them. I was interested in seeing how much inch pounds of torque it would take to remove these screws. The first screw came out at about 36-40in lbs.

    Torque setting for removal of gas key screws



    Once the screws were removed I looked at them and the gas key for any signs of adhesive. None was used. Using light torque, no adhesive and light staking is a recipe for disaster IMHO.

    As I said earlier, the gas key screws looked on the small side to me. I was right. My calipers tell me that they were on the small side and no amount of staking was ever going to get the sides of the gas key to touch the screws. So I changed them out for heat treated, aircraft certified torx screws.

    Size of the BM factory gas key screws


    Size of Torx bolts we replaced the factory gas key screws with



    I followed the following steps for the installation of the gas key:

    1. Degrease the gas key, bolts and bolt carrier.
    2. Verify that the gas key base is square.
    3. Apply a THIN coating of rocksett onto the torx screws.
    4. Torque down the screws to 60in lbs.
    5. Stake the gas key properly.

    Degreased bolt carrier, gas key and Torx screws



    Rocksett getting applied


    Torque setting for re-installation of gas key screws


    Gas key getting staked


    Finished product



    After the gas key was re-installed, I moved onto the bolt extractor. I changed out blue extractor insert for a black one and added a Crane O-Ring. I then upgraded the carbine buffer to an H buffer. Moving onto the castle nut, I double checked the torque setting on it and then staked it.

    Upgraded extractor


    Staked castle nut


    Factory Carbine buffer and installed H buffer




    The last issue that seems to plague many shooters is the low front sight base. This one was NOT rated for a flattop (F marked) and so I went ahead and installed a taller front sight post.

    Comparison of the two front sight posts (factory post on right)


    Taller front sight post installed



    Now we are all done and everything is good to go and back together. That wasn't so hard now was it?


    C4
    Last edited by C4IGrant; 01-23-12 at 16:45.

  2. #2
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    Finished product

    All done and ready to go!





    C4

  3. #3
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    Very thorough indeed!

    Are you sure the FSBs needed the sight post changed? I mean... is it possible they just didn't have an "F" stamped into them?
    "You people have too much time on your hands." - scottryan

  4. #4
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    Quote Originally Posted by demigod View Post
    Very thorough indeed!

    Are you sure the FSBs needed the sight post changed? I mean... is it possible they just didn't have an "F" stamped into them?
    I measured it and it was shorter than an F marked FSB. The taller front sight post just gurantees that the end shooter will be able to use whatever BUIS they want.


    C4

  5. #5
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    Very cool.
    Chief Armorer for Elite Shooting Sports in Manassas VA
    Chief Armorer for Corp Arms (FFL 07-08/SOT 02)

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    Excellent work! You should offer that as an upgrade package to all of the Bushmaster and other "tier 2" owners out there. My Stag came with the blue insert, standard buffer, and un-staked castle nut. I've fixed the first two but need to torque and stake the castle nut still.

  7. #7
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    Quote Originally Posted by JB2000 View Post
    Excellent work! You should offer that as an upgrade package to all of the Bushmaster and other "tier 2" owners out there. My Stag came with the blue insert, standard buffer, and un-staked castle nut. I've fixed the first two but need to torque and stake the castle nut still.
    I often times do, but generally BM owners tend to believe that their weapons are perfect and need no "upgrades."


    C4

  8. #8
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    Excellent upgrades Grant.

    This is the way Bushmasters should arrive from factory.

  9. #9
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    Quote Originally Posted by Paulinski View Post
    This is the way Bushmasters should arrive from factory.
    They should be matching the correct FSBs to flat top receivers. I can't believe they don't do so.
    "You people have too much time on your hands." - scottryan

  10. #10
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    Good Job!
    I'm glad to see that you took the suggestions of AR users and fixed BM's mistakes.
    If only BM would take those few extra steps and put out a properly assembled M4.


    I now know where my next major gun/accessories purchase will come from.
    -David

    AR-15 owner/shooter since 1998

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