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Stupid BCG Question

Discussion in 'Black Rifle Forum' started by dkf, Feb 14, 2013.

  1. dkf

    dkf

    5,433
    125
    Aug 6, 2010
    Got my BCM BCG and it comes with a small o-ring. What exactly is it for? A "Crane O-Ring" of the extractor?
     
  2. WoodenPlank

    WoodenPlank Who?

    7,958
    3
    May 15, 2010
    NW Florida
    Yes, that's the Crane o-ring. If you are having extraction issues (ie: extractor slipping off the rim of the casing too early during cycling) the o-ring gives extra tension on the extractor.
     


  3. F_G

    F_G

    1,050
    62
    Jan 11, 2010
    Crown King, AZ
    I have 4 BCM BCG's and they came with the "O" ring already installed plus an extra in a small sealed plastic bag, I'm guessing that's a spare they sent along.
     
  4. dkf

    dkf

    5,433
    125
    Aug 6, 2010
    So just leave it off unless I have issues? Going in a mid length upper.
     
  5. dkf

    dkf

    5,433
    125
    Aug 6, 2010
    Ok. I took the BCG apart to clean and reoil but did not remove the extractor. I'll just hold onto the o-ring.
     
  6. WoodenPlank

    WoodenPlank Who?

    7,958
    3
    May 15, 2010
    NW Florida
    Yep! :supergrin:
     
  7. fuzzy03cls

    fuzzy03cls

    2,855
    19
    Jan 28, 2010
    Florida
    None of my BCM's had the o ring pre installed?
    Basically. I added it on a few, & really see no difference other then trying to get the damn pin back into the extractor pin hole. PITA with the o-ring installed.
     
    Last edited: Feb 14, 2013
  8. dkf

    dkf

    5,433
    125
    Aug 6, 2010
    Well maybe I will strip the bolt down again and see if the o-ring is installed on it.
     
  9. dkf

    dkf

    5,433
    125
    Aug 6, 2010
    Tore the bolt down again. No o-ring from the factory.
     
  10. Warp

    Warp ΜΟΛΩΝ ΛΑΒΕ

    16,292
    293
    Jul 31, 2005
    Atlanta
    I don't know anybody that uses the o-ring. Hold onto it, but don't worry about it and don't use it unless you have a specific problem that diagnosis indicates use of the o-ring for.
     
  11. samuse

    samuse

    5,375
    21
    Jul 30, 2008
    South TX
    You'll generally only need it in suppressed SBRs.

    If you have a properly gassed mid length, you don't need it.

    I run nothing but 14.5" and 16" carbines (Colts and 1 BCM) and I've never needed the O-ring.
     
  12. ottomatic

    ottomatic

    1,297
    122
    Oct 15, 2002
    SW Tennessee

    That is exactly what I am looking to (eventually) put together. Suddenly I am worried! Please tell me why I am possibly going to have extraction issues. BTW - no full auto and intend on going with an adjustable gasblock.
     
  13. JimD303

    JimD303

    165
    0
    Nov 11, 2006
    PA
    I use them and recommend them in every configuration. They don't hurt anything and only add extractor tension... nothing wrong with that.
     
  14. samuse

    samuse

    5,375
    21
    Jul 30, 2008
    South TX
    Suppressed SBRs usually have much higher gas pressure in the chamber during unlocking/extraction. More extractor tension is beneficial because the case is actually being extracted before it fully contracts.
     
  15. samuse

    samuse

    5,375
    21
    Jul 30, 2008
    South TX
    If you don't need 'em, don't use 'em. The added tension can decrease the life of the extractor and the extractor pin and cause feed and ejection issues if the tension gets excessive enough.

    I like running a black insert and a Colt gold spring in carbines and mids. The O-ring would be ok if you were running a rifle spring and a blue insert in a carbine or mid gas.